A ball is thrown vertically upward with speed `10 m//s` and it returns to the ground with speed `8 m//s`. A constant air resistance acts. The minimum height attained by the ball is

Options

A. `5 m`
B. `4.5 m`
C. `3.5 m`
D. `4.1 m`

Answer

D

Explanation

Upward motion : `0 = (10)^(2) - 2 (g + (R )/(m))h` (i)
Downward motion : `(8)^(2) = 0 + 2(g + ( R )/(m))h` (ii)
Solving , `4 gh = 100 + 64 rArr h = 4.1 m`