Question

A Spherical Ball Of Mass 20Kg is stationary at the top of a hill of height 100 m. It rolls down a smooth surface to the ground and then climbs up another hill of height 30 m and finally rolls down to a horizontal base at a height 20 m above the ground. The velocity attained by the ball is:

Answer 1

Answer:

For the potential energy, only the difference between the initial and final points count.

So this difference is 100−20=80 m

Conservation of energy

2

1

mv

2

=mgh

0.5v

2

=10×80

⇒v=40 m/s

Option A.