The inertia is the tendency of objects to stay at rest or to keep moving with the same velocity.

1. Why does water comes out from a wet piece of cloth when you shake it?

Due to inertia of rest. When we shake the cloth, the water remains in its position and comes out.

2. Why do we fall forward, when a moving bus stops suddenly?

Lower part of our body come to rest but due to inertia of motion our upper part tends to move in the forward direction and we fall in the forward direction.

Inertia and Mass

All objects do not resist a change in their state of rest or motion equally. Massive objects resist more than lighter ones.

Mass is a measure of inertia.