What is Magnitude of Force: 7 Answers You Should Know


An external or internal agent that acts on a body to bring change in its physical appearance or motion is known as force. We will be discussing the magnitude of force.

The magnitude of the force is the measure of its strength to bring about the necessary change. Force has magnitude and also it acts in a particular direction. Force can be contact or non-contact. Almost all the day-to-day work is done by applying some force in one way or another.

When we push, pull, or lift an object, the measure of the force required to do the job is known to be its magnitude. Other forces like friction, gravitational pull, tension also have magnitude as their size. For instance, a muscle generates the force to some extent to extract the juice from lemon. When a ball falls downwards because gravity pulls it towards the ground. All these are the magnitude of forces.

To generate the general formula of the magnitude of the force the Second Law of Motion is considered. It states that the force applied to move an object has a magnitude equal to its rate of change of momentum, that is:

The measure of force is its magnitude

So,

F=k.(dp/dt)

[latex]F\propto \frac{\mathrm{dp} }{\mathrm{d} t}[/latex]

[latex]F= k \frac{\mathrm{dp} }{\mathrm{d} t}[/latex]

Here,

F= magnitude of the force

k = constant

p= momentum that is, [latex]ma[/latex]

The value of the k is taken to be unity, and hence the formula of force is:

F=d(mv)/dt

F=m.{d(v)/dt)

[latex]F=\frac{\mathrm{d(mv)} }{\mathrm{d} t}[/latex]

[latex]F=m\frac{\mathrm{d(v)} }{\mathrm{d} t}[/latex]

Since, dv/dt=a

Since, [latex]\frac{\mathrm{dv} }{\mathrm{d} t}= a[/latex]

F=ma

[latex]F=ma[/latex]

The S.I. unit of the magnitude of the force is N, that is, newton.

Effect of Magnitude of Force

The force has various impacts on the object. When the force of sufficient measure is applied on a body or an object, one of the following five effects is seen:

Move a stationary object.

An object at rest stays at the same position until an external agent acts on it. On exerting force on a stationary body, it starts displacing from its position and comes into motion. The magnitude of force determines how much the body would move and with what velocity.

For instance, a ball kept on the ground stays at its resting position. When someone kicks it, it comes into motion. The ball gets accelerated at a rate proportional to the intensity with which it is kicked. Hence the force tends to move the stationary object.

Stops a moving object

The other effect that the magnitude of force has on the object is to stop its motion. By applying force on a moving body, it can come to the rest position. The magnitude of force required to stop a moving body is majorly dependent on the body’s mass.

Stopping a moving elephant would require many people to apply force together and generate high magnitude. Whereas a moving ball will need only one person and significantly less force to stop. This is so because elephant mass is much greater than a ball, and thus it needs greater force to stop.

Change the direction of a moving object.

A moving body can change its direction after experiencing the force. A ball moving forward after striking a wall bounces back and changes direction. When a ball strikes the wall, the force is exerted on it, and it gets pushed backwards.

Changes shape or size of the object.

The magnitude of the force can also change the shape or size of the object. It can either increase or decrease the length. There is also a change in the shape of the body but sometimes this change is so minute that it is not visible to the eyes.

When we stretch a rubber band for quite a long time, the rubber gets elongated. That is, by applying the force, its size gets changed. Similarly, on squeezing the lemon, its shape gets deformed. Hence through these examples, it is clear that force shows impacts on the size and shape of an object.

Change the velocity of the object.

Car accelerating on applying force,
Image credit: https://pixabay.com/illustrations/delivery-truck-express-fast-3331471/

A body that is in motion can accelerate or decelerate when force is applied to it. On transmitting the force on a moving body its velocity changes.  By pushing the cycle which a cyclist is already riding, it gets accelerated as the velocity increases.

Frequently Asked Question (FAQs)

What is force?

The energy or strength that acts internally or externally on the body to change its state is known as force.

In simpler words, the strength applied to any object to either change its velocity, shape or position is known as force. We experience force or exert it in one way or the other. Opening a door or lifting a pencil is an example of force.

Is force a scalar quantity or vector quantity?

The fundamental quantities which only have magnitude are known as a scalar. Whereas those with magnitude and direction are vector quantity. Force is known to be a vector quantity.

What is magnitude of force?

The force is the energy or thrust applied to an object.

The strength or the size of the force that acts on a body is its magnitude. It is the numerical value of force. The strength that human muscles would need to lift a box would be considered the measure of force.

How is the magnitude of force derived?

The measure of the force is known as its magnitude.

The formula of the magnitude of the force is generated using Newton’s second law of motion. As per the law, the magnitude of force varies directly to the rate of momentum.

That is; [latex]F\propto \frac{\mathrm{dp} }{\mathrm{d} t}[/latex]

Hence, we get the formula;

F=ma

[latex]F=ma[/latex]

What is the example of the magnitude of force?

All our day-to-day activities can be explained by the concept of force. Either force acts on us, or we exert it.

A force must be applied to squeeze the toothpaste out. This force is of type push as the person has to push the paste outwards. It is pressed between the fingers. This is a general example of muscular force. Due to the impact of force, the shape of the paste gets deformed.

What are the effects of the magnitude of force?

The force can have the following five effects on the body:

  • Change the shape and size
  • Change the velocity
  • Change the direction
  • Stop a moving object
  • Move a stationary object

On what factors does the magnitude of the force depend?

The amount of strength is known as the magnitude of the force. It is basically the size of the force.

The magnitude of the applied force is dependent on the mass and the displacement of the object. More the mass of the body more would be the magnitude of the force to push or pull it.

What is the S.I. unit of the magnitude of force?

The standard unit for the magnitude of the force is named after Isaac Newton. Hence its SI unit is N, newton.

Rabiya Khalid

Hi,  I am Rabiya Khalid, currently pursuing my masters in Mathematics. Article writing is my passion and I have been professionally writing for more than a year now. Being a science student, I have a knack for reading and writing about science and everything related to it. If you like what I write you can connect with me on LinkedIn: https://www.linkedin.com/mwlite/in/rabiya-khalid-bba02921a In my free time, I let out my creative side on a canvas. You can check my paintings at: https://www.instagram.com/chronicles_studio/

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