Difference Between Rest and Motion With Examples

In physics, rest and motion are two different states of a body. In this post, we will learn about these two states and try to find out what is the difference between rest and motion.

A body is said to be at rest if its position does not change with respect to its surroundings. Whereas, when the position of a body changes with respect to its surroundings, it is said to be in motion.

The state of rest and motion of the body is relative to each other. A body can be both at rest and in motion at the same time.

Topics Covered:

• State of Rest with examples
• Definition or Rest in Physics
• State of Motion with examples
• Definition of Motion in Physics
• Rest and Motion are Relative

REST

If we look around us, we observe that many objects do not appear to move. Thus we consider them at the state of rest.

Examples for the State of Rest: 

1. A book lying on the table will not change its position if it is not disturbed. So, it is in a state of rest.
2. A bench in a park fixed under a tree is at rest as there is no change in its position.

Therefore, when the position of a body with respect to its surroundings does not change with time, the body is said to be at rest.

Definition of Rest in Physics

A body is said to be at rest if its position does not change with respect to a fixed points in its surroundings.

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MOTION

Unlike the above, we find that many things around us move from one place to another. A flying bird, a moving bus, a boy playing football, an oscillating pendulum of a wall clock, a moving train, a sailing ship, a walking man, etc. are some of the examples of motion

A moving object keeps on changing its position continuously with time with respect to a fixed point called the reference point.

Examples for Motion: 

1. When a moving car changes its position with respect to a tree or a lamp post by the side of the road, the car is said to be in motion.
2. A flying bird is also said to be in motion as it changes its position with respect to stationary objects such as trees.

Hence, when the position of a body with respect to its surroundings changes with time, the body is said to be in motion.

Definition of Motion in Physics

A body is said to be in motion if its position continuously changes with respect to its surrounding changes with time.

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One more example of rest and motion:

Suppose we are sitting on a railway platform and looking at a tree nearby. The tree is at rest because the tree does not change its position with respect to us. But when we see a train passing out of the station. The train is in motion because it is continuously changing its position with respect to us.

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REST AND MOTION ARE RELATIVE

A body can be both at rest and in motion at the same time. A body can be in motion relative to one set of objects while at rest relative to some other set of objects. Thus, rest and motion are relative.  To understand this, consider the following examples.

Examples for relativity in rest and motion:

1. Suppose you are lying on your bed. You are at rest in relation to all other objects inside the bedroom. But the room (or home) is on earth and the earth itself is not at rest. The earth is revolving around the sun. It takes one year to complete one revolution around the sun. Thus, along with earth, you are also revolving around the sun. Hence in relation to the sun, you are in motion.
2. Next, consider a boy sitting on a bench in a park looking at a bus passing by on a road. For the boy, the bus is in motion but the trees in the park appear to be at rest. But to a boy sitting inside the bus, the trees and boy outside the bus will appear to move in the opposite direction and the roof of the bus or driver of the bus will appear to be at rest.
3. If two trains move at the same speed and in the same direction on two parallel railways then both trains will appears stationary to the passengers sitting in them.

https://www.youtube.com/watch?v=bX0PsZkJXMY

Difference between rest and motion in terms of relativity. Video courtesy – CBSE@youtube

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Conclusion

Difference between rest and motion:

Thus, we conclude that a body while in motion with respect to a set of objects can appear at the same time in a state of rest with respect to some other set of objects (moving at the same speed and in the same direction). It is an observer and the surroundings that decide whether a given object is at rest or in motion.

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