Question

there are two balls slinding one through a straight track and the other along the track with a dip.

a) explain why the ball traveling on the track with the dip arrives to the end first.

b) what do you predict about the relative velocities of these two balls when they leave the end of the track? will one go faster than the other?

Answer 1

(a).

During the first part of the race, both the balls move together. Now, while the ball on the dipped track goes down, its horizontal speed increases. Hence, it goes ahead of the second ball. When it returns to its original level, it slows down to its original horizontal speed equal to the speed of the other ball. But it still remains ahead by a constant distance which it has moved ahead during the motion on the dipped track. Hence, it reaches the end first.

(b).

At the end of the track, their relative velocity will be zero. Hence, both the balls will move with equal velocity.