A body dropped from a height h with an initial speed zero, strikes the ground with a velocity `3km/h`. Another body of same mass is dropped from the same height h with an initial speed `-u' = 4km//h`. Find the final velocity of second body with which it strikes the ground

Options

A. 3km/h
B. 4km/h
C. 5km/h
D. 12km/h

Answer

C

Explanation

For 1st body
`v^2 = u^2 + 2gh rArr v^2 = 2gh rarr 2gh = (3)^2`
For 2nd body
`v^2 = (u)^2 + 2gh= (4)^2 + (3)^2= 5^2 rArr v = 5km//h`