Two balls `A and B` of same masses are thrown from the top of the building `A`. Thrown upward with velocity `V and B`, thrown downward with velocity `V`, then

Options

A. Velocity of `A` is more than `B` at the ground
B. Velocity of `B` is more than `A` at the ground
C. Both `A and B` strike the ground with same velocity
D. None of these

Answer

C

Explanation

Let both the balls are thrown from height 'h', both will move under same acceleration i.e., acceleration due to the gravity.
Let the speed of ball 'A' when it reach the ground is `V_A`.
For ball `A` using `v^2 = u^2 + 2 gh`
`(V_A)^2 = V^2 - 2 gh rArr V_A = sqrt(V^2 - 2 gh)`
Let the speed of ball 'B' when it reach the ground is `V_B`.
For ball 'B' again using `v^2 - u^2 + 2gh`
`(V_B)^2 = (-V)^2 - 2 gh rArr V_B = sqrt(V^2 - 2gh)`.