Question

Define a) Rest b) Motion. Why are these terms called relative? Give an example for each.

Answer 1

Step1: a) Rest

One object is said to be at rest if the position of that object doesn't change with respect to time.

Example:

Consider a person sitting on a moving train, then that person is considered to be at rest with respect to the train.

Step2: b) Motion:

Motion is the process of moving, changing place, or even changing position with respect to its surroundings in a given interval of time.

Example:

Rotation of the fan, a rolling ball, a moving car, etc.

Step3: Rest and motion are relative

1. Rest and motion are relative terms.
2. A body at rest with respect to one observer may be in motion with respect to another observer.
3. The Rest and motion of an object depend on the frame of reference.
4. If the observer is at rest in his own frame of reference, he may be moving in another observer's frame of reference.
5. A body can be at rest and in motion at the same time.

For example,

We know that Earth is rotating in its own orbit around the sun. so, the earth is in motion with respect to the sun.

If the person is at rest on the surface of the earth, With respect to the sun, that person is in motion.

But, with respect to the earth, the same person is at rest.

Hence, Rest and motion are relative terms.