Question

Explain Inertia of rest with an example.

Answer 1

Hint: The body at rest tries to stay in the same state of rest due to inertia. When it is made to move by applying an external force on it, this inertia tries to resist this change and tries to keep the body in the same state of inertia.

Complete answer:
Inertia is defined as the tendency of a body to stay in state of rest or of motion. Unless an external force is applied on it, it maintains the same previous state because of inertia. The inertia of a body is directly proportional to its mass. Greater the mass of a body, greater is its inertia and more it resists the change in its state of rest or motion.
Example:
Now, when a person is sitting in a car at rest, due to inertia the person stays at rest. Now when the car starts moving then the lower part of the body of the person which is in contact with the car moves with the car but the upper part of the person’s body is still at rest. The inertia of rest of the lower body is overcome by the motion of the car but the upper body’s state of rest resists this change and the person tends to fall backwards as the car starts moving. Eventually, the inertia is overcome by the motion and the whole body gets in state of motion with the car.

Note:
When the car comes to a stop, then the person falls forward because of inertia of motion as lower comes to rest with the car but the upper body tries to stay in motion due to inertia.
The inertia of direction can be experienced when the car abruptly changes direction and the upper body tries to stay in the previous direction of motion.