Abhishek

Hi ....I am Abhishek Khambhata, have pursued B. Tech in Mechanical Engineering. Throughout four years of my engineering, I have designed and flown unmanned aerial vehicles. My forte is fluid mechanics and thermal engineering. My fourth-year project was based on the performance enhancement of unmanned aerial vehicles using solar technology. I would like to connect with like-minded people.

19 Example Of Reversible change: Detailed Explanations

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This article discusses about example of reversible change. As the name suggests, reversible changes are those changes whose effect can be reversed.

Reversible means something that can be traced back to its original form. This article discusses about different types of changes that take place. Then we will discuss about reversible change in particular and then see different examples of reversible change.

What is a reversible change?

A reversible change is that type of change which can be reversed. After a subject undergoes this type of change, it can attain its original form back.

Reversible change is also called as a physical change. This is mainly because physical changes can be reversed, chemical changes are hard to reverse. Hence the term physical change. We shall see more about types of changes and examples of reversible change in later sections of this article.

Types of changes

There are many types of changes taking place around us but they can be classified broadly into two types. These types are discussed below-

  • Reversible or physical change – This type of change is not permanent and the subject can be brought back to its original form once it undergoes a reversible change.
  • Irreversible or chemical change – This type of change is permanent and it is impossible to bring the subject back to its original form once it has undergone irreversible change.

Examples of reversible change

We can see innumerable examples of reversible changes happening around us. These examples are discussed in the section given below-

Melting of ice

Melting of ice is a reversible change as the melted ice can be converted back to ice by freezing it below zero degrees. We can do this as many times as we want as the water can be turned into liquid and then again be converted back to ice by freezing it.

Boiling of water

Boiling water is a reversible change as the boiled water gets converted to steam. This steam can be converted back to liquid water by condensing it. Condensation is the process of converting the steam back to liquid water.

example of reversible change
Image: Boiling

Image credits: user:Markus Schweiss, Kochendes wasser02, CC BY-SA 3.0

Falling of remote

When a remote falls, it is not going to be there forever. We can pick it up and put back to the original place. Hence it can be said that falling of a remote is a reversible change as the remote can attain its original place.

Folding a paper

Folding of paper is a reversible change as the paper can be unfolded to its original form. This can be done by simply folding the paper in an opposite direction.

Ironing of clothes

Ironing of clothes can be considered as a reversible change because the clothes can get crease again if we put them shabbily. Hence, we can attain the creases back making ironing process a reversible change.

Inflation of balloons

Inflating balloons is a reversible change This can be explained by the fact that the air can come out of same inlet from where we pumped the air inside the balloon. The balloon will attain its original shape back after getting deflated hence this is a reversible change.

Stretching of rubber band

A rubber band has potential energy stored in it. When it is stretched this potential energy gets stored inside the rubber band and when the force is released, this potential energy brings back the rubber band to its original shape. Hence this is a reversible change.

Compressing a spring

Compression of spring is similar to stretching of a rubber band. When the spring is compressed or stretched the potential energy gets stored inside the spring. As soon as the force is lifted the potential energy gets converted to kinetic energy and so the spring comes back to its original form. This makes compressing/stretching of a spring a reversible change.

Melting of wax

Melting wax is a reversible change as it gets frozen again to regain its original form.

Bending of aluminium pipe

Aluminium is a ductile material and hence an aluminium can be bent easily. This bent pipe when bent in oppsite direction leads the pipe to attain its original form. Hence we can say that bending an aluminium pipe is a reversible change.

Bending of copper wire

Bending of copper wire is a similar example as that of bending of aluminium pipe. We can attain the original shape of copper wire once it is bent. Hence we can say that bending of copper wire is a reversible change.

Heating of pan

Heating of pan is a reversible change as the pan can attain its original temperature once the source of heat is cut off. The pan comes to the ambient temperature when the heat source is cut off, hence we can say that heating of pan is a reversible change.

Heating of oil

Heating of pan and heating of oil are similar examples. Oil will attain room temperature once the heat source is cut off. This way it can be said that heating of oil is a reversible change.

Freezing water

Freezing of water can be considered as reversible change as the water can be brought back to liquid state just by keeping it outside the refrigerator for a while.

Defrosting of food

Defrosting means heating the frozen food so that the food becomes moist. This can be reversed by frosting the food again in the refrigerator. Hence this can be considered as reversible change.

Freezing of food

Freezing of food is considered as a reversible change as the food can be defrosted again as discussed above.

Spilling of water

When water is spilt on the floor, let us say from a container. We can simply use a dry cloth to absorb the water from the floor. Then squeeze the water out of the cloth into the container. This way the water gets back to the container in which it was lying originally. This makes spilling of water as a reversible change.

Bruises and cuts

Bruises and cuts are reversible as the skin gets healed by the white blood cells and makes the injury look like it was never there.

Wetting of clothes

When the clothes get wet, they are not going to be permanently wet as evaporation is going to take place. The clothes will be dried up soon. This way wetting of clothes becomes a reversible change.

Wetting of hair

Wetting of hair is a similar example as that to wetting of clothes. The hair can be dried up by using a hair dryer. This way wetting of hair becomes a reversible change.

Also Read:

19 Example Of Pyramid: Detailed Explanations,Facts

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Pyramids

This article discusses about example of pyramid. We all have a basic idea of what a pyramid is. When we hear the word pyramid, we promptly start thinking about Pyramids Of Giza.

Well, pyramids are more than just the structures at Giza. In general, pyramids are polyhedron formed by connecting a base polygon to a point or apex. Each base edge and the apex form a triangle. Hence, we relate pyramids to triangles. This article discusses about definition of pyramid and real life examples of pyramid.

What is a pyramid?

As discussed in above section, pyramid is a polyhedron that is formed by connecting a base that is polygon shaped and a point that is called as apex.

Apex and every base edge forms a triangle. Hence a pyramid consists of multiple triangles. For a pyramid having a polygon base of n sides, there are n+1 faces and vertices and 2n edges. We shall discuss more about pyramids in further sections of this article.

Types of pyramids

There are many types of pyramids which can exist. Almost infinite number of pyramids. These types depend on the number of sides the base polygon has.

Only the most commonly seen pyramids are discussed in the section given below-

  • Triangular pyramid– When the base polygon is a triangle then it is said to be a triangular pyramid.
  • Square pyramid– When the base polygon is a square that means the length of each side of the base polygon is equal then the resulting pyramid is known as square pyramid.
  • Pentagonal pyramid– When the base polygon has five sides then the resulting pyramid is called as pentagonal pyramid.
  • Circular pyramid– When the base polygon is a circle, then the resulting pyramid is called as circular pyramid.

Example of pyramid

There are innumerable objects around us that are pyramids. Let us see some of the daily life examples of pyramids. They are given below-

Pastries and cake

When pastries and cakes are cut from centre and a piece is taken out, that piece resembles the shape of a pyramid. The cakes and pastries itself can be made in the shape of a pyramid.

Toys

Many toys such as a triangular rubix cube are in the shape of a pyramid. This type of rubix cube is made up of small triangles.

Monuments

Many monuments are made in the shape of pyramids. Such as the famous Pyramids Of Giza. These are the most common examples of pyramids. Infact we think of these Pyramids at Giza when we hear the term pyramid.

example of pyramid
Image: Pyramids Of Giza

Image credits: Wikipedia

Tent

A tent is in the shape of a pyramid. A tent has a square base. The apex is connected with the edges of the base and forms triangles at the sides. Hence a tent can be considered as a pyramid.

Transmission lines tower

Transmission lines have a broad base that acts as the base polygon and narrow tip which acts as the apex of the pyramid. The transmission lines are situated at the apex of this pyramid. Hence, we can say the shape of transmission lines resemble a pyramid.

Transmission lines tower

Buildings

Many buildings are made in such a way that they resemble a pyramid. These architecture ideas are taken from the ancient architecture. The best example of ancient architecture are the pyramids of Giza which have pyramid shape.

Temples

Many temples resemble the shape of a pyramid. They are broader at the base resembling the base polygon and has an apex point that connects directly to the base. Hence we can say that many temples have a shape of pyramid.

Water melon piece

When we cut a water melon from centre and remove a slice of it, we can say that the piece resembles a pyramid. This slice is nothing but a small pyramid.

Wet floor sign board

A wet floor sign board can be seen around corridors and halls where there is a chance of public slipping. These sign boards have a broad base and an apex connecting this base polygon. We can safely say that a wet floor sign board is an example of pyramid.

Outside line pyramids used in sports

In sports, small plastic pyramids are used to mark the corner point or outside line of the play area. This can be used as goal post also. These are examples of pyramids.

Chocolate

Chocolates can be moulded into many shapes and forms. Majorly, chocolates are square and circular. But we can see triangular chocolates in the market too. These triangular chocolates resemble the shape of a pyramid.

Paperweights

Most paper weight have the shape of a pyramid. They are mere show pieces made of glass which have small design structures inside them. These design structures carry most part of the weight of these paper weights. The paper weight used to put weight on the paper so that that do not fly away. These can be considered as pyramids.

Paperweights

Fancy water bottles

Some water bottles have a broad base resembling a base polygon and an apex that connects to this base. These type of water bottles have a shape of a pyramid.

Pillars

Pillars are mostly cylindrical or cuboidal but some places have pillars that have the shape of a pyramid. These pillars are broader at the base and narrower at the apex.

Buttons

In some shirts, we have designer buttons that have a shape of pyramid. These buttons will have a broader base and narrower apex that connects to the base polygon.

Mountains

Mountains are yet another common examples of pyramid. They have a very broad base and a narrow apex that connects to the base. Height of a mountain can reach upto 8000 mt on Earth!

Roof top

Some houses made up of wood have a pyramid shaped roof. This type of design is used in regions where snowfall is a problem. The triangular structure will help the snow to slide down easily which incase of flat roof would not have been possible.  

Temple top (known as Shikhara)

Temple tops known as Shikhara have a shape of pyramid. They have a broad base and a narrow apex that connects the base and forms a pyramid.

Plant pot designs

Some pots have a design resembling to a pyramid. These pots have a broad base which make room for the soil and a narrow apex making way for the plant to grow.

Also Read:

5 Example Of Prism: Detailed Explanations

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Prism

Tis article discusses about example of prism. We will not be limiting our discussion to optical prisms only which are used to refract light, but in later sections we will also discuss about regular non optical prisms.

A phenomenon of light in which it changes its path of travel after passing through a medium of different refractive index. This phenomenon is called as refraction of light. A prism is one such example of medium which has a different refractive index than air and hence is used to change the direction of light.

Example of rectangular prism

A rectangular prism also called as cuboid is a geometrical structure defined by three quantites, that are- length, breadth and height.

The examples of rectangular prism are given below-

  • Book- A book has all the three– Height, length and breadth. Hence it can be considered as a rectangular prism.
  • Cupboard– A cupboard may have many shapes but cupboard having a rectangular cross section can be considered as rectangular prism. It has all the three- height, length and breadth.
  • Bottle of cuboidal shape– A cuboidal shaped bottle will have length, breadth and height with a rectangular cross section. Hence it can be said to be a rectangular prism.
  • Buildings– Buildings most commonly have a rectangular cross section and fulfil all the requirements of a rectangular prism.
  • Cuboidal bar– A cuboidal bar satisfies all the requirements of a rectangular prism that it has a rectangular cirss section, length, breadth and height.
  • Deck of cards– Deck of cards can be considered as a rectangular prism as it has all the properties of a rectangular prism. An individual card makes the depth of the deck.
  • Mobile phones– Usually the mobiles have a rectangular cross section. They can be considered as rectangular prism.
  • Water tank– A water tank usually has a rectangular cross section and can be considered as a rectangular prism.
  • Laptop– A laptop when in closed condition can be considered as a rectangular prism.
  • Canvas board– A canvas board has a rectangular cross section and satisfies all the requirements of a rectangular prism and hence it can be considered as a rectangular prism.
  • Living room– Living room or in that case any room can be considered as a rectangular prism.
  • Door– A rectangular door meets all the requirements of a rectangular prism and can be considered as a rectangular prism.
  • Bed– Usually the beds are cuboidal in shape. Cuboidal beds are considered as rectangular prism.
  • Mobile charger– A mobile chargers adaptor can be considered as a rectangular prism.
  • Blackboard– Blackboard has everything a rectangular prism needs that is length, breadth and depth. Hence it can be considered as a rectangular prism.
  • Containers– Rectangular containers can be considered as rectangular prism.

Examples of triangular prism

Triangular prism is that type of prism which has a triangular cross section. For a prismatic structure to be triangular, it should have atleast two triangular faces and three rectangular faces.

example of prism
Image: Triangular prism

Image Credits: D-Kuru, Prism-side-fs PNr°0117, CC BY-SA 3.0 AT

The examples of triangular prism are give below-

  • Tent– A camping tent is an example of triangular prism because it has two triangular faces and three rectangular faces.
  • A piece of pizza pie– A piece of pizza pie is nearly a triangular prism as it has a triangular cross section.
  • A piece of apple pie– Similar to pizza pie, a piece of apple pie also resembles a triangular prism.
  • A piece of water melon- When we cut a slice of watermelon from centre, then it resembles a triangular prism.
  • A piece of cake– A cake slice when cut from its centre resembles to a triangular prism.
  • A piece of cheese block– A cheese block when cut from its center resembles a triangular prism.
  • Optical prism– An optical prism is used to refract light. When it has a triangular cross section, it can be considered as a triangular prism.
  • A house shaped like triangular prism– Generally wooden houses have a triangular cross section. It can be considered as a triangular prism.

Example of pentagonal prism

A pentagonal prism is slightly different from a conventional prism. It has five sides at the top and bottom faces. A pentagonal prism can be said that it is an extruded version of a pentagon (Shape having five sides with equal interior angles)

The examples of pentagonal prism are given below-

  • Pentagon Headquarters at USA– The Pentagon HQ at USA is a builidng having five sides of equal length. This is a perfect example of pentagonal prism.
  • A pentagonal rubix cube- A rubix cube with five equal sides is a pentagonal prism.
  • A container having pentagonal cross section- A tiffin box or a container having a pentagonal cross section is considered as a pentagonal prism.
  • A pentagonal nut– A nut having five sides of equal length is considered as a pentagonal prism.
  • A gift box with five sides- A gift box having five sides of equal length is considered as pentagonal prism.
  • Optical prism with five sides– An optical prism is used to refract light, when the prism has five sides, it can be said to be a pentagonal prism.
  • Buildings with five sides– A building having five sides instead of four can be considered as a pentagonal prism.

Example of Hexagonal prism

Hexagonal prisms are similar to pentagonal prism with the only difference being the number of sides in the cross section. A hexagonal prism has six number of sides in its cross section.

The examples of hexagonal prism are given below-

  • Residential buildings having six sides- Residential buildings with six sides of equal length are considered as hexagonal prism.
  • A gift box having six sides- A gift box which has six sides will be considered as hexagonal prism.
  • A hexagonal nut– A nut usually has six sides of equal length. It can be said to be a hexagonal prism.
  • Honey comb structure– Honeycomb structure is made by stacking multiple hexagons together. These hexagons are nothing but small hexagonal prisms.
  • Trusses– A truss is a support structure made using cylindrical bars. When these trusses are arranged in a shape of hexagon, the structure can be said to be hexagonal prism.
  • Hexagonal optical prism- An optical prism is used for refracting light, when it has a hexagonal cross section then it can be said to be a hexagonal prism.
  • Wooden pencils– Wooden pencils have hexagonal cross section for a better grip. Hence penciles can be said to be hexagnal prism.

Example of Square prism

A square prism is similar to a rectangular prism. The primary difference between a sqaure prism and rectangular prism is that length of each side is same for a square prism.

The examples of square prism are given below-

  • Buildings with square cross sections– A building having a square cross section with same measurements of length breadth and depth can be said to be a building that is also a square prism.
  • An optical prism having four equal sides– An optical prism used for refracting light can be considered as a square prism if it has equal length breadth and depth.
  • A bottle with square cross section– A bottle with a square cross section and equal measurements of length breadth and height is considered as a square prism.
  • A cupboard with square cross section– A cupboard with square cross section and of same height as that of length and breadth is considered as a square prism.
  • A water bottle with square cross section– A water bottle having a square cross section and same height as that of length and breadth is considered as square prism.
  • A square tiffin box– A square tiffin box with same length breadth and height is considered as a sqaure prism.
  • Deodorant box– A compact deodorant box can be considered as a square prism if all the sides have equal lengths.
  • Cooler packaging– A cooler packaging box has equal lengths, it can be considered as a square prism.
  • Refrigerator packaging box– A double door refrigerator can be considered as a square prism as it has same measurement of length breadth and height.
  • A pen stand- A pen stand has same length breadth and depth. It can be considered as a square prism.
  • A square container– A square container has a square cross section and equal length breadth and height, hence it can be considered as a square prism.

What is refraction?

As discussed in above section, it is the phenomenon in which the direction of light is changed when passed from one media to another.

The change in direction occurs due to different refractive indices of the two mediums through which light is travelling. Fro example, when the light passes through a prism then the direction of travel changes and gets refracted. We shall study about refractive index in the later sections of this article.

What is refractive index?

Refractive index of a material is the measure of solute present in an aqueous solution. It is also a measure of how the light wll change its speed and direction after passing through a media with different refractive index.

The refractive index of vacuum is considered as 1. Glasses and other materials will have refractive indices more than one meaning that the speed of light will be lesser in those media than the speed of light in vacuum.

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5 Radioactive Decay Types: Uses, Properties And Examples

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Alpha

This article discusses about radioactive decay types. We know that atoms are held together by a force called interatomic force or nuclear force.

When an unstable atom wants to attain a stable state, it does so by emitting a large amount of energy through radiation. This extra energy being the reason behind instability of that atom is shredded by the atom itself. This phenomenon is called as radioactivity. We shall read more about radioactivity in this article.

What is radioactivity?

As discussed in above section, it is the phenomenon in which the unstable atom loses its energy to attain stability.

The energy released is termed as nuclear or atomic energy as it is derived from the nucleus of the atom. We shall study more about radioactivity and its types in further sections of this article.

Radioactive decay types

There are many ways in which the nuclear energy can be emitted. The different types of radioactive decay are listed below-

Alpha decay

Alpha particles are those particles which consists of two protons and two neutrons (Like He atom). When the nucleus emits alpha particles in a reaction then it is called as alpha decay.

radioactive decay types
Image: Alpha Decay

Image Credits: Wikipedia

Beta decay

Just like Alpha decay, in Beta decay, the Beta particles are emitted. Beta particles are those particles which have a pair consisting of positron and neutrino or electron and anti neutrino. When positron and neutrino are emitted, it is termed as beta plus decay and similarly when electron and anti neutrino are emitted it is termed as beta minus decay.

Gamma decay

Gamma decay takes place in two steps. First nucleus emits Alpha or Beta particles and leaves the nucleus in an excited state. To achieve a stable state, nucleus emits gamma ray photons. This is called as gamma decay.

Neutron emission

In some cases, due to excessive Alpha Decay or Beta Decay, the remaining nuclei become neutron rich. These neutrons are shedded away by the process of neutron emission. This results in formation of Isotopes of different particles.

Electron capture

Sometimes, Nucleus may capture an orbiting electron. This leaves the proton alone due to which it gets converted to neutron. During this process, Neutrino and gamma rays are emitted.

Cluster Decay

In Cluster decay a nucleus heavier than Alpha particle is emitted.

Radioactive decay series example

An unstable atom undergoes a series of radioactive decays or transformations to attain a stable state. This series of transformations is termed as radioactive decay series.

A radioactive decay series is also called as radioactive cascade, the atom does not get directly converted to a stable state. Rather it undergoes many transformations to reach a stable state. Examples of radioactive decay series is given below-

  • Thorium series– In Thorium series, following elements are present- Actnium, Bismuth Lead, Polonium, Radon, Radium and Thallium. The total energy release from Thorium-232 to Lead-208 is 42.6 MeV.
  • Neptunium Series– In Neptunium series, only two isotopes are involved namely Bismuth-209 and Thallium-205. The total energy release from Californium-249 to Thallium-205 is 66.8 MeV.
  • Uranium Series– Uranium series contains the following elements- Astatine, Bismuth, Lead, Polonium, Protactinium, Radium and Radon, Thallium and Thorium. The total energy release from Uranium-238 to Lead-206 is 51.7 MeV.
  • Actinium series– The Actinium series consists of- Actinium, Astatine, Bismuth, Francium, Lead, Polonium, Protactinium, Radium, Thallium, Thorium and Radon. The total energy released from Uranium-235 and Lead-207 is 46.4 MeV.

Radioactive decay properties

We have discussed in above sections that radioactivity is the phenomenon in which an atom reduces its energy to attain a stable state. The energy released through these atoms is high enough to make an Atom bomb.

The process of radioactive decay is very random, one cannot simply tell which atom is going to disintegrate into which atom. The entire energy release process is spontaneous. The transformation theory does not tell about the particular cause inside the atom which is responsible for the emission of this extra energy.

Radioactive decay uses

Although, humans have a dangerous threat of nuclear radiation. A slight amount of exposure to radiation can cause illness, burns and severe diseases which can lead to death. Excessive amount can cause instant death.

But it can be used in a better way if the energy is harnessed in a proper manner. Let us see some uses of radioactivity-

  • Medicine– Cobalt-60 is used extensively to trap cancer cells. This is a major breakthrough in fighting cancer.
  • Electricity generation– Uranium-235 is a commonly used fuel in nuclear power plants. Even a small amount of Uranium-235 can be used to generates megawatts of electricity.
  • Treatment– Iodine-131 is used in treating hyperthyroidism. Some radioactive isotopes are used in diagnostic purposes as well as for research.
  • Measurement of thickness-The strength of penetrations if these radioactive elements can be used precise measurement of thicknesses of plastics and metals in industries.
  • X rays-X rays and CT scans employ radioactive elements which penetrate through the human skin and give a luminiscent view of human body from inside.

Radioactive hazards

If not used in a proper manner, exposure to radiation can cause irrepairable damages to human body as well as other life on Earth.

Below is a list of few of the hazards that are caused by exposure to radioactivity-

  • Skin burn– Long exposure to sun can cause burns on skin. This can be observed by tanning that is darkening of the skin. If the skin is exposed to sunlight for a very long time, then it can have permanent damage and sometimes cause skin cancer.
  • Radiation burns- When a person comes in direct contact with radioactive material, depending on the amount of exposure to this radiation, he/she can get radiation burns. The skin gets burnt due to the high penetration power of radioactive elements.
  • Acute radiation syndrome- This is an illness caused by intake of high amount of radiation in a very short amount of time.
  • Cancer– Radiation can cause cancer in our bodies.
  • Cardio Vascular diseases– Excessive radiation causes cardio vascular diseases which can be there for entire lifetime and can be passed on genetically.
  • Radiation cloud– Atomic blasts leave a huge radiation cloud in the atmosphere thus polluting the atmosphere with radioactive elements. These radioactive clouds then come down in the form of rain.
  • Loss of life on Earth– Due to radiation, the innocent plants and animals die because they are unaware of the threats caused by radiation in their bodies.
  • Lengthy half life of radioactive materials– Once there is a radioactive leak in an area, it has to be completely sealed for thousands of years as the half life of radioactive elements is far more than human lives. Thus to curb the effect of radiation, the entire population has to shifted and the area needs to be sealed.

Boiling Point And Atmospheric Pressure: What, How, Relation And Facts

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This article discusses about the relation between boiling point and atmospheric pressure. We all have this misconception that the boiling point of a liquid depends on the temperature. This is not true.

Temperature plays an important role in boiling but there is another factor which is responsible for boiling to take place. That is vapour pressure. This vapour pressure when reaches the value of atmospheric pressure outside the system, the liquid starts boiling.

What is vapour pressure?

Vapour pressure is the value of pressure exerted by the surface of the liquid when it is about to change its state to gaseous.

The temperature is increased to make the vapour pressure value reach the value of pressure of ambient. As temperature increases the pressure of the liquid also increases. This law is called as Gay-Lusaac’s law in thermodynamics.

Image credits: user:Markus Schweiss, Kochendes wasser02, CC BY-SA 3.0

Define boiling point using atmospheric pressure and vapour pressure

We all have seen boiling water atleast once in our life time. It is the point at which the liquid phase of a substance changes into gaseous phase.

Whenever this happens the ambient pressure and vapour pressure of the liquid will have same values. To achieve this equality, temperature of the liquid is increased continuously. As the temperature increases, pressure also increases. Boiling is observed by droplets of liquid rising up.

Does boiling point depend on atmospheric pressure?

Definitely yes. As we have discussed that vapour pressure when reaches the value of atmospheric pressure, boiling takes place.

If the value of atmospheric pressure is itself less, then it will take lesser amount of time for vapour pressure to touch the value of atmospheric pressure. This way the boiling point will be lower as compared to places where ambient pressure is more.

Effect of atmospheric pressure on boiling point

We have clearly discussed in above section regarding the effects of atmospheric pressure on the boiling point of a substance.

In a nutshell, we can say that atmospheric pressure and boiling both are directly dependent on each other, if one changes then other one also changes. They both are directly proportional to each other that is if one quantity increases other one will also increase. If the liquid starts boiling faster than surely the atmospheric pressure outside would also be low.

How to increase atmospheric pressure?

Atmospheric pressure mainly depends on the gravity. Due to gravity, the molecules are attracted to the surface.

So the atmospheric pressure will be more where the effect of gravity is more. In simple words, the places which are closer to the Earth’s surface (sea level), those places will have more atmospheric pressure than the places having more altitude.

Why does boiling point vary with atmospheric pressure?

Until now we have discussed a lot about effect of atmospheric pressure on boiling point in early sections of this article. They both are directly related to each other and boiling point is dependent on the value of atmospheric pressure outside the system.

This is because when the vapour pressure at the surface of the liquid starts getting higher and getting closer to the value of atmospheric pressure, then the boiling starts taking place. If the value of atmospheric pressure is low then the liquid will start boiling very easily ad faster.

How do atmospheric pressure and elevation affect boiling point?

Gravity. Gravity is the main reason behind the entire episode of boiling point’s dependency on elevation and atmospheric pressure.

Gravity is more at Earth’s surface and gets slightly lower as we go higher. Due to gravity, the molecules in the atmopshere get closely packed near the surface and are slightly scattered at higher elevations. We know the direct affect of atmospheric pressure and higher altitudes on boiling point of a substance.

Boiling point and atmospheric pressure equation

Clausius Clapeyron Equation gives us a direct mathematical relationship between atmospheric pressure and the boiling point.

Using this equation, a person can find the values of boiling point for different vapour pressure if only value of boiling point with its corresponding temperature is given. The equation is given as follows-

Where will the water boil faster, surface or at the hilltop?

After discussing so many points regarding affect of atmospheric pressure and elevation on the boiling point, now we can answer this question easily.

At the surface level, the atmospheric pressure is more and at the hill top the atmospheric pressure is less. So it is safe to say that the water will boil faster at the hill top due to low atmospheric pressure. It will take less time for the vapour pressure of water to reach a value equal to the atmospheric pressure.

What is cavitation?

Cavitation is related to boiling. It takes place inside a liquid when the local vapour pressure becomes lesser than the vapour pressurevery rapidly.

Cavitation is the localised boiling of the liquid particles that can be observed by bubbles and voids forming in the liquid. Cavitation is undesirable because it damages the mechanical components used in the machine.

What is Bernoulli’s equation?

The Bernoulli’s equation is given for incompressible fluids flowing in a streamline flow. This equation tells us that for a fluid moving in a stream line flow, the fluid particles will have constant energy throughout.

In simple words, Bernoulli’s equation tells us that: Static pressure+dynamic presusre= total pressure.

What happens to atmospheric pressure as we move upwards?

As we move upwards, the effect of gravity becomes lesser. Hence, the molecules in the air get scattered and are loosely packed.

Due to this, the atmospheric pressure value decreases. When we say this, the boiling point of a substance is getting directly affected. Due to low atmospheric pressure the boiling point of the substance will also go down.

What is the boiling point of water at standard pressure conditions?

At standard atmospheric conditions, the atmospheric pressure is considered as 1 atm or 1.01 x 10^5 Pa.

At this point, the water will boil at 100 degrees Celsius or 212 degrees Fahrenheit. The conversions of units can be done by using their respective conversion formulae. In Kelvin, the boiling point temperature is 373.15 Kelvin.

13 Diffuse Reflection Examples: Detailed Insight And Facts

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Scattering

This article discusses about diffuse reflection examples. Reflection is simply the bouncing back of light whenever it falls on a polished surface.

The reflection can be of many types depending upon the type of object it is falling on and the environmental conditions. This article will discuss about the definition of diffuse reflection first, and then about diffuse reflection examples.

What is reflection?

Before knowing about diffuse reflection, let us first get a clear idea on what is the true meaning of reflection.

Reflection is nothing but the bouncing back of light. This happens when it falls on a polished or shiny surface. Due to this phenomenon we can see different types of images in mirrors. The image type depends upon the type of mirror or the reflecting surface.

What is diffuse reflection?

In specular reflection, the incident ray will fall on the reflecting surface and get reflected back in one direction only. Whereas in diffuse reflection the case is not the same.

In diffuse reflection, the incident ray falls on the mirror and gets reflected back into multiple directions. This is something which does not happen in conventional specular reflection. This type of reflection takes place due to the rough nature of the reflecting surface.

How diffuse reflection is formed?

The sole reason for a reflection to be diffused is the surface of the reflecting object. When a rough surface is used for reflection, diffuse reflection takes place.

Diffuse reflection is quite normal because no matter how polished a surface is, irregularities are always there. And where there are irregularities, there is diffuse reflection. Even tiny imperfections can cause diffuse reflection.

Diffuse reflection example

Every thing we see around is a result of diffuse reflection taking place. If we see closely, no object is completely smooth. They all have some irregularities taking place. Now these irregularities are what causes diffuse reflection.

Let us look at some examples of diffuse reflection given below-

Bicycle reflectors

These reflectors are made in such a way that when light falls on them they illuminate spreading red light in multiple directions.

Clothing

Clothes absorb some of the light and reflect some of the light. For example black coloured clothes absorb major part of the light falling on it whereas white clothes will reflect most of the light falling on it.

Paper

A paper acts as transluscent film which allows only a certain portion of light to pass through and reflects remaining light in to multiple directions.

Butter paper

Butter paper also absorbs some portion of the light and reflect remaining part of the light in other directions.

Translucent film

As discussed above, a transluscent fil will reflect some of the light in multiple directions.  

Cardboard

A cardboard has a rough surface which results in uneven reflection of light or diffuse reflection.

Rough surface finish on wood

An improper finish on wood will produce uneven reflection.

Car body covered with dust

Dust particles get settled on the car’s surface creating a rough surface. This roughness causes diffuse reflection when light rays fall on the car’s surface.

Metals covered with dust

Dust particles act as irregularities on the surface of the metals. These irregularities will produce diffuse reflection.

Plastic toys having scratches on it

Plastic toys will show specular reflection when their surfaces are polished but will show diffuse reflection when there are scratches on it.

Rough plywood

A rough plywood won’t completely reflect the light as a polished plywood does. The light will be reflected in multiple directions giving out an improper reflection.

Glass having scratches

Scratches act as irregularities and thus give rise to diffuse reflection.

Phone cover with broken glass

A broke glass will make the reflecting surface uneven. Uneven surfaces will give rise to diffuse reflections.

Materials with matte finish

Matte finish is a rough finish which produces hazy images of the objects places near them. This is also an example of diffuse reflection.

Uses of diffuse reflection

Almost everything we see around the world is due to diffuse reflection taking place. The uses of diffuse reflection are given below-

  • Camera– A camera uses diffuse reflection principle to capture vivid objects.
  • Absorption spectra/ Spectroscopy- Diffuse spectroscopy is used to find the absorption spectra of powdered samples in those cases where transmission spectroscopy won’t work.
  • Coloured objects- Colours of objects are determined by the average deflection of the wavelength of light.
  • Importance for vision– Almost everything we see around us is due to diffuse reflection. Only those things which emit light on their own for example sun and those reflections coming out of polished surfaces are not an example of diffue reflection. The sky is blue in colour due to Rayleigh scattering and is an example of diffuse reflection.
  • Interreflection– in Computer graphics, to achieve global illumnation, difuse interreflection is used.

Diffuse reflection vs Regular reflection

The table below shows the differences between diffuse reflection and regular reflection-

Diffuse reflection Regular reflection
The incident ray is scattered in multiple directions. The incident ray is scattered only in one direction.
Forms a blurry image.  Forms a clear image.
 It can happen that no image is formed  It forms an image always.
 Happens on rough surfaces.  Happens on smooth surfaces only.
Table: Difference between diffuse reflection and regular reflection

Diffuse reflection vs scattering

The table shown below gives the differences between diffuse reflection vs Scattering. Although both may appear similar but have many differences associated with them.

Diffuse Reflection Scattering
In diffuse reflection, absorption does not take place. In scattering, the light waves undergo complete absorption and then the waves are scattered/dispersed.
The wavelength of the light does not get changed. The wavelength of the light changes after scattering takes place. The best example is the colour of sky when sunlight is scattered by the atmosphere.
The waves bounce up after falling on the reflecting surface.  The waves get absorbed by the surface and then they are dispersed in multiple directions.
Table: Difference between diffuse reflection and scattering
diffuse reflection examples
Image: Scattering

Image credits: KCVelaga, Electron-scattering, CC BY-SA 4.0

What is specular reflection?

Specular reflection is the conventional reflection which takes place when a ray of light falls on a reflected surface and gets bounced back in a single direction.

This is the case that usually takes place when light falls on a smooth and polished surface. The examples of specular reflection include- reflection from a conventional mirror, water bodies etc.

What causes diffuse reflection?

In the above section, we got an idea about how a diffuse reflection take place Let us dig deeper into its mechanism.

When the light rays fall on a rough surface, the light rays are actually hitting a plane having a lot of irregularitites. Due to these irregularities, the reflected rays also get an irregular direction causing an uneven reflection or diffuse reflection.

Also Read:

15 Classical Conditioning Examples: Detailed Explanations

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This article discusses about classical conditioning examples. Conditioning can be defined as invoking stimulus from someone with the help of neutral stimulus and unconditioned stimulus.

It so happens with our brains that it attaches random things with our favourite things even though they are not related to each other. This happens when those random things were present when the favourite thing was about to take place. This creates a pleasant memory about the random thing. Let us discuss more about this in detail.

What is an unconditioned stimulus?

An unconditioned stimulus is used in classical conditioning that brings out an automatic response from the subject.

This kind of stimulus is generally related to the subject’s interests. For humans it can be money, food, opposite gender, travel places, hobbies like playing and painting etc. We will discuss more about such stimulus and their related responses in this article.

classical conditioning examples
Image: Classical Conditioning of Dogs

Image Credits: Salehi.s, Classical Conditioning Diagram, CC BY-SA 4.0

Examples of unconditioned stimulus

There can be various kinds of unconditioned stimulus, they depend on the subject’s field of interests. Following are the examples of unconditioned stimulus-

Feather tickling your nose

When a feather tickles your nose, we immediately give a response so as to get rid of the tickling. This is a type of unconditioned stimulus.

Cutting up an onion

When an onion is cut, the chemicals inside the onion make humans cry. This is an immediate response given by humans and hence considered as an unconditioned stimulus.

Animal running to its food

For an animal the food is a type of unconditioned stimulus. This so happens because after looking at the food, the animal gives an immediate response.

Humans getting excited over salary day

A salary day is nothing but the first day of the month. Humans get excited over this date and hence the salary day can be considered as an unconditioned stimulus.

Kids getting excited for PT period’s bell

After hearing the bell for PT period, students get excited so as they know now is their playing time. This specific bell brings out an immediate response in students and hence the bell can be considered as an unconditioned response.

A song that reminds you of some person

When you hear a song, we can sometimes recall someone after hearing the song. This happens as a result of the song being an unconditioned stimulus for you.

Smell from chinese food makes us sneeze

Chinese food is filled with some spices which bring you lots of sneezes. When we go near the chef who is preparing chinese food, we immediately start sneezing. This can be considered as unconditioned stimulus.

Examples of classical conditioning

Now we know the meanings of neutral stimulus, classical conditioning and unconditioned stimulus. We can now look at some examples of classical conditioning to get a clearer idea of what actually it is.

Training a dog with whistle and its favourite food.

Here the whistle acts as an unconditioned stimulus. We can observe that after bringing food with the whistle, the dog starts responding to whistle alone also. This is an example of classical conditioning.

Students getting excited over PT period’s bell

Students don’t get excited over any normal bell unless it is PT period’s bell. If their tone of bell is different then even if the bell is for someone else, the students will immediately get excited.

Training our mind to stay up after hearing alarm bell

After hearing the alarm tone for a long time, then our brain starts responding to it the same way even if we hear the bell in the evening time.

Wearing football jersey whenever you go our to play with kids

If we wear football jersey every time we go to play football with kids, then even after we are going somewhere else, the jersey will remind the kids of football only. This is an example of classical conditioning. Here jersey acts as an unconditioned stimulus.

Carrying office bag to office

Carrying office bag to office becomes a routine. After some while if we take that bag somewhere else, then we will immediately think of office because that bag acts an unconditioned stimulus.

Oiling your hair before sleeping

If we make oiling an habit then after some time the oil will remind us of sleeping even if it is not bed time. Oil acts as the unconditioned stimulus here.

Brushing your teeth before sleeping

Brushing teeth before sleeping also becomes a routine and hence when we brush our teeth at an odd time, it will remind us of sleeping.

Switching on the TV after you come home

If we have a habit of switching on TV every day after coming home, then we will feel weird if one day we decide to not switch on the TV. This is also a response given to the unconditioned stimulus that is TV.

Hearing the sound of laptop when it is switched on

Hearing this sound will often create a memory in our brains. When we hear this sound from other laptops, it will remind us of our laptop.

Celebrities in advertising

Celebrities in advertisements leave a particular image in our minds. When we see those celebrities somewhere else we get reminded of the original ad.

Aromas in restaurants

Aromas in restaurants also act like unconditioned stimulus. A similar aroma will remind us of that restaurant.

Smartphone tones

Smart phone tones are usually common in all phones. These tones will remind us of our own phone when we hear them from somebody else. This is a perfect example of classical conditioning. We will get up thinking it is our phone.

Fear of dogs

Fear of dogs from a childhood experience will create a huge repulsion from dogs even hitting adult age. This is because our brain gets conditioned that way.

Exam anxiety

Exam anxiety triggers our brain to study more out of tension. This is also an example of classical conditioning.

Recess bell

Recess bells are generally different than other bells. They are longer than usual, so when students hear this bell they get immediately excited about the recess time. This is also an example of classical conditioning.

Holiday music

After listening to music on holidays, we will get reminded of that place after we hear that music somewhere else. This is a perfect example of classical conditioning,

What is neutral stimulus?

Neutral stimulus as the name suggests holds no interest value in itself. It is just a conventional way of gaining someone’s attention.

A neutral stimulus includes a whistle, a cry for help from a person you want to avoid etc. The subject does not feel like reacting to such kind of stimulus. For subjects to start reacting to such stimulus, we need to perform conditioning. Let us study about classical conditioning in sections given below.

What is classical conditioning?

Now as we have learnt the definitions of neutral stimulus and unconditioned stimulus, we can define classical conditioning.

It is the way of mixing neutral stimulus with unconditioned stimulus to get a conditioned response from a subject. This is done to train the subject’s mind to give response to neutral stimulus.

Also Read:

15 Specular Reflection Examples: Detailed Insight And Facts

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Reflection 1

This article discusses about specular reflection examples. The phenomenon of bouncing back of light when it falls on a polished surface is called as reflection.

Specular reflection is very common and typically means a mirror like reflection. It can be observed in our day to day lives. This article first discusses about what is reflection, types of reflection and then about different examples of specular reflection.

What is reflection?

As discussed in above sections, the light bounces back after falling on a polished or shiny surface. This phenomenon is called as reflection.

When we see ourselves in the mirror, it is due to reflection. Only polished surfaces can reflect back the light completely. The light will pass through the glass if it is transparent from both the sides. One side has to be opaque in order for the glass to exhibit reflection. We will discuss about how reflection takes place in below sections of this article.

What is specular reflection?

Specular reflection is a type of reflection which means mirror like reflectance of light when it falls on a shiny body.

Specular obeys the law of reflection. The angle made my incident ray and normal is the same as the angle made by reflected ray and normal. We shall see more about law of reflection and mechanism of reflection in below sections.

specular reflection examples
Image: Specular reflection on water body

Image credits: Wikipedia

What is scattered/diffuse reflection?

In scattered reflection, the rays of reflection are unevenly scattered in all directions unlike specular reflection.

In diffuse reflection, the reflected rays make unequal angles with the vertical. The reflected rays scatter in multiple directions rather than one.

Examples of specular reflection

Specular reflection can be observed every where in our day to day lives. Whenever we go out in public places or even sit inside our classrooms, specular reflection can be observed in some or the other way.

Let us see more about specular reflection by looking at some examples. They are given below-

Conventional plane mirror

A conventional rectangular plane mirror like we see in washrooms and wardrobes follow the principle of specular reflection. The incident rays come from the object standing in front of the mirror, these incident rays are reflected back at the same angle. Here, the angle of incidence is zero hence the reflected ray also makes zero degrees with the normal meaning both incident ray and reflected ray co incide each other. The object’s reflection will be visible. 

Concave mirrors

In concave mirrors, we can usually see an inverted image because of the curvature of concave mirrors.

Glasses on the side walls of malls/shops

Glasses on the side walls of malls are cleaned thoroughly, this way the glasses become a polished surface. Hence we can see our own reflection on the glasses when we go near those glasses.

Polished ceramic mug

A ceramic mug also acts like a mirror when it is polished properly. We can see our own reflection when we are holding the mug.

Glare on sunglasses

When we clean the sunglasses, they become polished surfaces. Hence a person standing in front of us can see their reflection from our sunglasses.

Steel utensils

Steel utensils also act like polished surfaces. We will be able to see reflection of the object if it is placed near to the mirror. Metal body phones- Metallic finish acts like a polished surface, any light falling on such a surface is reflected back.

Car body

A car body is usually made of glass fiber on which a polished finish is given. Due to polished finish, we can see our reflections when we stand beside a car. A dirty car won’t be able to reflect our image as it is not polished.

Water body

A water body such as lakes and rivers are usually still and reflects the objects near them. A perfect example of this is reflection of sky in the river and lake. The lake appears to be blue because of reflection of sky.

Polished plastic surface

When a plastic surface is polished, we can see our reflection on it. This is also due to specular reflection.

Ionospheric reflection

Radio waves are reflected in ionosphere. This is an example of specular radiation of waves.

Reflection of radar waves

When the enemy aircraft enters our air base, our radar detects it. This happens because the radar waves are reflected back to the radar after striking on aircraft.

Acoustic mirrors

Even sound can be reflected using acoustic mirrors. This is an example of specular reflection of non electromagnetic waves.

Atomic mirrors

Atoms can be reflected using atomic mirrors. They also follow specular reflection.

Glossy paper

A glossy paper that are used in crafts and decorative purposes also reflect the light. This is also an specular reflection.

Scissors with fine finish

Most scissors are made with metallic alloys and plastics. Both materials when polished give a fine reflection.

Pupil of eye

Pupil of eye also reflects light, when we see other person in the eye then we can observe our reflection in it.

How does specular reflection works?

In above sections, we have discussed what specular reflection is. Now we will discuss how the specular reflection works.

When an incident ray of light strikes a polished surface (also called as specular surface), it gets reflected back with an exact angle at which the incident ray struck on the surface. A person standing in the path of reflected ray will be able to observe the image of the source object from where the incident ray was coming.

How to calculate specular reflection?

Specular reflection can be calculated with the help of Phong Model which was developed by computer graphics researcher Bui Toung.

The specular reflection is a dot product of two vectors. The formula is given below:

Specular reflection= V.R

Where, V is the viewing direction

R can be given by the formula given below-

R=2.(N.L)N-L

Where,

L is the incident light direction

Law of reflection

In optics, there three defined laws of reflection. They are given below-

  • The angles made by incident ray and reflected ray with the normal are same.
  • The incident ray, reflected rays and the normal all three exist in same plane.
  • Both the incident ray and reflected ray are on the different sides of normal.

Does specular reflection obey law of reflection?

Specular reflection obeys the law of reflection. It satisfies all the conditions that laws of reflection require. The incident ray makes an equal angle with the normal as reflected ray makes.

With that, reflected ray will be on one side of the normal and incident ray will be on the other side of normal. Then most importantly, all the three- normal, incident ray and reflected ray lie on the same plane. Hence, we can say that specular reflection obeys all three laws of reflection.

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17 Mirror Reflection Examples: What, How, Detailed Facts

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Reflection

This article discusses about mirror reflection examples. We all are aware of what mirrors are and how we can see our reflections in it.

This article will discuss about different types of mirrors, the type of reflections they produce and then finally discuss the examples of mirror reflections. We need to keep in mind a simple fact throughout that is mirrors reflect all the incident light falling on them.

What is a mirror?

Mirror is a polished object made of glass which is painted on one side and polished on other. It is used to reflect the light completely such that we can see virtual image of the objects (incase of plane mirrors).

The paint is applied on one side so that it does not allow the light to completely pass through the glass. The light will reflect back with the same angle at which it was incident. Let us discuss more about mirrors in later sections of this article.

Types of mirrors

A conventional mirror is one that is in rectangular shape. We all use that mirror for looking at our reflections. In reality there are two more types of mirrors that are used in Physics. They are- convex mirrors and concave mirrors.

Let us read more about these mirrors in the section below-

  • Plane mirror/rectangular mirror– A plane mirror is a flat mirror which are usually used in our homes and malls to see our own reflections. The light falls at zero degrees with the normal and hence the reflected ray also makes zero degrees with the normal. This way we can see our reflection in the plane mirrors.
  • Concave mirror– Concave mirrors as the name suggests makes a cave like mirror surface. They can make both virtual and real iage depending on the distance of the object from the focus. A spoon’s inner surface is an example of concave mirror.
  • Convex mirror– Convex mirror is a mirror bulged outwards. This mirror is usualy used in rear view mirrors and on the crossings of road. The out side of spoon is an example of convex mirror.

What is mirror reflection of light?

When light falls on an object, the light may be absorbed, reflected or transmitted through the object. These three things may also take place partially, that is light may get partly absorbed, partly reflected and partly transmitted.

When this light reflected completely after falling on the object, it is called as specular or mirror reflection of light. The image of the object can be seen with no loss of resolution as the light gets reflected completely.

Mirror reflection examples
Image: Reflection on water body

Image credits: Wikipedia

How does mirror reflection work?

We are aware now that mirror is made up of glass which is painted with grey or black colour on one side and polished on other side.

When the light falls on mirror, the light travels through the glass but does not get through the grey paint. This trapped light is reflected back at the same angle at which it was incident. The image of the object is then observed with no loss of resolution as the light gets reflected completely.

Mirror reflection examples

We all know about mirrors and their uses. Let us discuss some of the examples where we can see mirror reflections. The examples are given below-

Wardrobe mirrors

Wardrobe mirror is an example of plane mirror. We can see our reflections of the same size as that of ours.

Mirrors at changing rooms in malls

Mirrors at changing rooms are also an example of plane mirrors. They are also used for obseving our own reflections in the mirror.

Reflection on water bodies

Reflection on water bodies may be considered as a reflection on plane mirror. We can see the water body appearing as blue in colour because of the reflection of blue sky. The colour of the sky is reflected to our eyes hence we observe that the water is blue.

Mirrors at barber shops

Mirror at barber shops are examples of plane mirror. At barber shops, the mirrors are arranged in such a way that we can even see the back of our heads in the mirror.

Concave mirrors used in labs

In Physics lab, we can observe many types of mirrors out of which one is concave. Thir mirror creates an inverted image of the object when it is located near to the mirror and an enlarged virtual image when it is located farther from the mirror.

Rear view mirrors

Rear view mirrors use convex mirrors. They create slightly enlarged ojects, this is why there is a text written on those mirrors “objects may appear closer than they actually are”

Car body

When a car is cleaned and polished properly, we can observe our own reflection on it.

Pupil of eye

The images formed on the pupil of eye are very small but we can observe them. When a person standing infront of us looks closely into our eye, he/she can observe his/her reflection in our eyes.

Steel spoon

As steel spoon when cleaned acts as a concave mirror and created inverted image when we place an object near to it.

Steel bowl

A steel bowl acts as a convex mirror which akes enlarged images of objects kept near to it.

Steel plate

A steel plate acts as a plane mirror which makes virtual images of same size as that of objects that are kept near to the plate.

Metal objects

Metal objects when polished properly reflect away most of the light falling on them.

Polished plastic toys

Plastic toys when cleaned properly also reflect away most of the light. We can see our reflection on plastic toys once we finish cleaning them.

Tinted windows

Tinted windows don’t allow all the light to enter inside the room during day time, reflecting away most of the light. This way we can see our reflections in this windows if we are standing outside of the room.

Ceramic mugs

Ceramic mugs when polished act as convex mirror and hence we can see our own reflections in it.

Ceramic plates

Ceramic plates when polished act as plane mirrors hence we can see our image of exact same size as that of ours.

Optic fibers

Optic fibers use the principle of total internal reflection. The fibers are sized in such a way that the light will keep reflecting itself and travel from one place to another without losing much of its intensity. Many internet providers use this technology to provide high speed internet.

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Is There Friction with Constant Velocity?

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is there friction with constant velocity

Yes, there can be friction even when an object is moving at a constant velocity. This is because friction is a force that opposes motion, and it does not necessarily depend on the acceleration of the object. In this comprehensive blog post, we will explore the concept of friction in detail, providing measurable and quantifiable data to support the understanding of this phenomenon.

Understanding Frictional Force and Applied Force

When an object is moving at a constant velocity, the net force acting on it in the direction of motion must be zero. This means that the frictional force (Ff) is equal to the applied force (Fa) in the opposite direction.

For example, consider a box being pushed along a rough surface with a constant velocity of 2 m/s. If the applied force is 10 N, the frictional force must also be 10 N, ensuring that the net force is zero and the object maintains its constant velocity.

The relationship between the frictional force and the applied force can be expressed mathematically as:

Ff = Fa

where Ff is the frictional force and Fa is the applied force.

Coefficient of Friction

is there friction with constant velocity

The coefficient of friction (μ) is a measure of the frictional force between two surfaces. It is typically represented as a ratio of the frictional force to the normal force (N) between the surfaces.

The frictional force can be calculated using the following formula:

Ff = μ * N

where Ff is the frictional force, μ is the coefficient of friction, and N is the normal force.

For instance, if the coefficient of kinetic friction between a box and a surface is 0.35, and the normal force is 50 N, the frictional force would be:

Ff = μ * N
Ff = 0.35 * 50 N
Ff = 17.5 N

The coefficient of friction can be determined experimentally or obtained from reference tables for various material combinations.

Free-Body Diagrams

Free-body diagrams are a useful tool in visualizing the forces acting on an object. When an object is moving at a constant velocity, the frictional force and the applied force are equal and opposite, as shown in the diagram below:

+---------------+
|  Applied Force  |
+---------------+
|  (Fa)          |
+---------------+
|  Frictional Force  |
|  (Ff)          |
+---------------+

This diagram clearly illustrates the balance of forces, where the frictional force opposes the applied force, resulting in a net force of zero and a constant velocity.

Examples and Calculations

  1. Box Pushed on a Rough Surface:
    Consider a box with a mass of 5 kg being pushed along a rough surface with a constant velocity of 2 m/s. The applied force is 25 N, and the frictional force is 2.6 N.

Using Newton’s second law, we can calculate the acceleration of the box:

F = ma
0 = m * a
a = 0 m/s^2

Since the net force is zero, the acceleration is also zero, indicating a constant velocity.

  1. Box Pulled Vertically Upward:
    Suppose a box with a mass of 1.2 kg is being pulled vertically upward at a constant speed of 0.3 m/s. The coefficient of kinetic friction between the box and the surface is 0.2.

To calculate the frictional force, we can use the formula:

Ff = μ * N

The normal force (N) in this case is the weight of the box, which can be calculated as:

N = m * g
N = 1.2 kg * 9.8 m/s^2
N = 11.76 N

Substituting the values, we get:

Ff = μ * N
Ff = 0.2 * 11.76 N
Ff = 2.352 N

The frictional force acting on the box is 2.352 N, even though the box is moving at a constant velocity.

These examples and calculations demonstrate that friction can indeed exist when an object is moving at a constant velocity. The frictional force opposes the motion, ensuring that the net force is zero and the object maintains its constant velocity.

Factors Affecting Frictional Force

The frictional force between two surfaces can be influenced by several factors, including:

  1. Surface Roughness: The rougher the surfaces, the higher the frictional force.
  2. Normal Force: The greater the normal force between the surfaces, the higher the frictional force.
  3. Coefficient of Friction: The coefficient of friction depends on the materials in contact and their surface properties.
  4. Velocity: The frictional force may slightly decrease as the velocity increases, but this effect is generally small at constant velocities.
  5. Temperature: Changes in temperature can affect the surface properties and the coefficient of friction.

Understanding these factors can help in predicting and analyzing the frictional forces acting on objects moving at constant velocities.

Numerical Problems

  1. A box with a mass of 10 kg is being pushed along a horizontal surface with a constant velocity of 2 m/s. The coefficient of kinetic friction between the box and the surface is 0.3. Calculate the frictional force acting on the box.

Given:
– Mass of the box, m = 10 kg
– Velocity of the box, v = 2 m/s
– Coefficient of kinetic friction, μ = 0.3

Solution:
The normal force (N) acting on the box is equal to its weight:
N = m * g = 10 kg * 9.8 m/s^2 = 98 N

The frictional force can be calculated using the formula:
Ff = μ * N
Ff = 0.3 * 98 N
Ff = 29.4 N

  1. A block with a mass of 5 kg is being pulled up a vertical surface at a constant speed of 0.5 m/s. The coefficient of kinetic friction between the block and the surface is 0.2. Calculate the force required to pull the block.

Given:
– Mass of the block, m = 5 kg
– Velocity of the block, v = 0.5 m/s
– Coefficient of kinetic friction, μ = 0.2

Solution:
The normal force (N) acting on the block is equal to its weight:
N = m * g = 5 kg * 9.8 m/s^2 = 49 N

The frictional force can be calculated using the formula:
Ff = μ * N
Ff = 0.2 * 49 N
Ff = 9.8 N

The force required to pull the block at a constant speed is equal to the frictional force:
Fa = Ff = 9.8 N

These numerical problems demonstrate the application of the concepts discussed earlier, allowing you to calculate the frictional forces acting on objects moving at constant velocities.

Conclusion

In conclusion, the presence of friction is not limited to situations where an object is accelerating. Even when an object is moving at a constant velocity, friction can still exist and play a significant role in the dynamics of the system. By understanding the relationship between frictional force and applied force, the concept of the coefficient of friction, and the use of free-body diagrams, we can effectively analyze and quantify the frictional forces acting on objects moving at constant velocities.

The examples and calculations provided in this blog post illustrate the practical applications of these principles, enabling a deeper understanding of the role of friction in constant velocity scenarios. This knowledge is crucial for students and professionals in the field of physics, as it allows for accurate predictions, analysis, and problem-solving in various real-world situations.

Reference:
1. Friction and Constant Velocity
2. Friction and Newton’s Laws
3. Coefficient of Friction