A ball is thrown vertically upwards from the ground. If `T_1` and `T_2` are the respective time taken in going up and coming down, and the air resistance is not ignored, then

Options

A. `T_1gtT_2`
B. `T_1=T_2`
C. `T_1 lt T_2`
D. nothing can be said

Answer

C

Explanation

Air resistance (let F) is always opposite to motion
(or velocity)
Retardation in upward journey
`a_1=(F_1+mg)/m=g+(F_1)/m`

Acceleration in downward journey
`a_2=(mg-F_2)/m=g-(F_2)/m`
Since, `a_1 gt a_2 rArr T_1 lt T_2`