NEET2015PhysicsWork, Power and EnergyActual
A ball is thrown vertically downwards from a height of 20 m with an initial velocity v 0 . It collides with the ground, loses 50 percent of its energy in collision and rebounds to the same height. The initial velocity v 0 is: (Take g = 10 m s - 2 )
Options
- A20 m s - 1
- B28 m s - 1
- C10 m s - 1
- D14 m s - 1
Correct answer
A. 20 m s - 1
Step-by-step solution
kinetic energy of the ball on reaching ground K E 1 = m g h + 1 2 m v 0 2 after collision K E 1 2 = m g h m g h + 1 2 m v 0 2 2 = m g h v 0 = 2 g h = 20   m     s − 1