An athlete often runs before taking a long jump. This is an example of :

1. Newton's first law
2. inertia of rest
3. inertia of motion
4. both (a) and (c)

In inertia of motion, the body continues to be in a state of motion with …………… speed in …………… direction unless an external force is applied.

1. variable, zigzag
2. same, same
3. same, variable
4. variable, same

Is force needed to keep a moving body in motion?

A ball is moving on a perfectly smooth horizontal surface. If no force is applied on it, will it's speed decrease, increase or remain unchanged?