Is Gravity A Conservative Force: 3 Important Concepts


Gravity, a derived quantity from the gravitational force is conservative in nature. Let us take a brief look at how is gravity a conservative force.

Gravity is also a conservative force, which means that the total amount of work required to displace an object from one position to another is independent of the path taken.

Image Credits: DECHAMMAKL, Gravity 9218, CC BY-SA 4.0

How is gravity a conservative force?

To understand the answer to this question, first, we need to know what is the meaning of conservative force.

The force is said to be conservative when the total amount of work required to moving an object from one position to another is not dependent on the path. Now the gravity is said to be a conservative force because it satisfies the above principle of a conservative force just like the electrostatic force satisfies the principle. Let’s see an example to understand the question is gravity a conservative force.

Is Gravity A Conservative Force

Conservation of gravity

To understand is gravity a conservation force, let us see two cases as follow:

  • Case I:  Let us consider a block of mass m kept on the ground position A as shown in the figure below. The work is done in order to take this block from ground position A to some position B at height h as shown in the figure. So here the total work done by the gravity can be given as

W = Fh

∴ W = mgh ………. (1)

Is Gravity A Conservative Force
  • Case II: Now let us consider the same block of mass m on the ground at position A is now taking to position B at the same height h but along a different path from AC to CD to DE to EB, as shown in the figure.
Is Gravity A Conservative Force

The work done by gravity to move this block along a path AC+CD+DE+EB can be given as

W = WAC + WCD + WDE + WEB ………. (2)

Since, WCD  =  F. s = Fs cos𝛉

As the force is acting vertically downward, 𝛉 = 90° 

Therefore WCD = Fs cos (90°) = 0 ………. (3)

Similarly, 

WEB = 0 ………. (4)

From equation (3) and (4), equation (2) becomes,

W = WAC + WCD + WDE + WEB

∴ W = WAC + 0 +  WDE + 0

∴ W = WAC +  WDE

∴ W = F. displacement along AC + F. displacement along DE

∴ W = F. (AC + DE )

∴ W = mg (h)

∴ W = mgh ………. (5)

From equations (1) & (5), we can say that the total work required to move a block of mass m is not dependent on the path taken and is equal to mgh in both cases. Hence, gravity is a conservative force.

Let us see one more example to know about how is gravity a conservative force.

The following picture shows that the ball is thrown up high in the sky. As it moves up, the gravitational force does negative work and decreases potential energy. After reaching a certain height, the ball starts to move down where gravitational force does positive work and increases potential energy. Therefore the total effort done on the ball is zero irrespective of the path and hence the gravity is said to be a conservative force. 

Is Gravity A Conservative Force

As the overall work done is not dependent on the path, gravity is the conservative force.


FAQ’s

Q. What is the meaning of gravitational force?

Ans: A natural event that happens between two things that are separated by a large distance and that causes them to move.

Newton’s law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.”

Where F = Force of gravitation

m1 & m2 = masses of the objects

r = distance between the objects

Q. What is the meaning of gravity?

Ans: The attraction between the earth and other objects.

Gravity is a naturally occurring phenomenon that occurs between the surface of the earth and an item that is located somewhere in the sky.

As we all know, the mass of the earth is enormous, and it is important to remember that an object with a larger mass attracts an object with a lower mass. As a result, it is claimed that the force of gravity is attractive in nature since the earth draws any body that is in close proximity to the ground. It is given as,

F = mg ,

Where F = Force of gravity,

m = mass of an object,

g = acceleration due to gravity = 9.8 m/s²

Q. How to differentiate gravity and gravitational force?

Ans: Gravity is a part of gravitation.

Gravitation is defined as the force that acts between two bodies. While gravity is nothing but a force that solely exerts between the surface of the earth and a body in its surroundings.

The gravitational force is what holds the earth, the sun, and the atmosphere together. This is owing to the fact that our planet’s gravitational force is maintained. Not only that, but it also assists us in keeping a safe distance between the star and the sun.

Q. What are the different examples of the effect of gravity?

Ans: There are several examples of gravity effects in our surroundings.

  • Due to the force of gravity, the gases in the sun are kept together.
  • Water sitting at the base of a glass and floating at the top of the glass is due to gravity.
  • The ocean’s tides are caused by the force of attraction between the earth’s surface and the moon. Gravity has a role in this as well.
  • The revolution of the moon around the earth is the result of the force of gravity.

Prajakta Gharat

I am Prajakta Gharat. I have completed Post Graduation in physics in 2020. Currently I am working as a Subject Matter Expert in Physics for Lambdageeks. I try to explain Physics subject easily understandable in simple way.

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