Suppose that the three balls shown in figure start simultaneously from the top of the hills. Which one reaches the bottom first ? Explain.

Explanation

Ball from first hill reaches the bottom first.
Reason :
1) In the first hill, the ball has uniform rectilinear motion.
2) So, the speed and velocity have same magnitude and direction.
3) In the second and third hills, the ball takes curved path.
4) So, the direction of velocity changes.