External force is needed to make a stationary body move as well as to stop a moving body.
To understand this chapter i.e. Laws of Motion, lets have a quick recap on what we already know about Motion.
- Motion in simple is tendency to move. An object is said to be in motion when it changes its position with time
- A body is said to be at Rest if it is not moving
- An external force is always involved in motion. This force helps body to perform required actions and these actions are according to rules or laws i.e. Laws of Motion.