Motion in a Straight Line - Result Question 37
38. A boy standing at the top of a tower of $20 m$ height drops a stone. Assuming $g=10 ms^{-2}$, the velocity with which it hits the ground is
(a) $10.0 m / s$
(b) $20.0 m / s$
(c) $40.0 m / s$
(d) $5.0 m / s$
[2011]
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Answer:
Correct Answer: 38. (b)
Solution:
- (b) Here, $u=0$
We have, $v^{2}=u^{2}+2 g h$
$\Rightarrow v=\sqrt{2 g h}=\sqrt{2 \times 10 \times 20}=20 m / s$
