Question

A stone is dropped from a certain height which can reach the ground in 5 second. If the stone is stopped after 3 second of its fall and then allowed to fall again, then the time taken by the stone to reach the ground for the remaining distance is

• A. 2 sec
• B. 3 sec
• C. 4 sec
• D. None of these

Answer 1

Answer: (C)

4 sec

Answer 2

Total distance $= \frac{1}{2}gt^{2} = \frac{25}{2}g$

Distance moved in 3 sec $= \frac{9}{2}g$

Remaining distance $= \frac{16}{2}g$

If t is the time taken by the stone to reach the ground for the remaining distance then

$\Rightarrow \frac{16}{2}g = \frac{1}{2}gt^{2} \Rightarrow t = 4\mspace{6mu}\sec$