Kinematics Question 180

Question: A stone is dropped into water from a bridge 44.1

m above the water. Another stone is thrown vertically downward 1 sec later. Both strike the water simultaneously. What was the initial speed of the second stone

Options:

A) 12.25m/s

B) 14.75m/s

C) 16.23m/s

D) 17.15m/s

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Answer:

Correct Answer: A

Solution:

Time taken by first stone to reach the water surface from the bridge be t,

then h=ut+12gt244.1=0×t+12×9.8t2

t=2×44.19.8=3 sec

Second stone is thrown 1 sec later and both strikes simultaneously.

this means that the time left for second stone =31=2 sec Hence 44.1=u×2+129.8(2)2
44.119.6=2uu=12.25 m/s



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