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
1) 2 sec
2) 3 sec
34 sec
4) None of these
​

Answer 1

total time=5 sec

stopped at=3 sec

again allowed to fall down,time taken =5sec-3sec

=2sec

Answer 2

Answer: 3) 4 sec

Explanation:

First, find the height from which the stone was dropped =(1/2)×g×t² = (1/2)×10×5×5 = 125m

Vertical distance travelled in initial 3s = (1/2)×10×3×3 = 45m

Remaining distance = 125-45 = 80m

Time taken by the stone to reach the ground for the remaining distance is =

80 = (1/2)×10× t²

t² = 16

t = 4 sec