Question

A ball is thrown vertically downwards from a height of 20m with initial velocity V it collide with the ground and loses 50% of its energy in the collision and rebounds to the same height the initial velocity V is equal to

Answer 1

Answer:

Initial energy Ei=PE+KE=mgh+ 21mv²

Energy when it reaches the ground: E= 1÷2mv²

since PE is zero.

Given, E= 1÷2

Ei Since it rises to the same height Ef =mgh+0 is the final energy

⇒ 21 (mgh+ 21 mv 2)=E

f =mgh+0 v

2 =2gh=2×10×20=20

2

⇒v=20m/s