Wave Mechanics Question 816
Question: A stone is dropped into a lake from a tower 500 metre high. The sound of the splash will be heard by the man approximately after
[CPMT 1992; JIPMER 2001, 02; Kerala PMT 2005]
Options:
A) 11.5 seconds
B) 21 seconds
C) 10 seconds
D) 14 seconds
Show Answer
Answer:
Correct Answer: A
Solution:
The time taken by the stone to reach the lake $ t _{1}=\sqrt{( \frac{2h}{g} )}=\sqrt{( \frac{2\times 500}{10} )}=10,sec $ (Using $ h=ut+\frac{1}{2}gt^{2} $ ) Now time taken by sound from lake to the man $ t _{2}=\frac{h}{v}=\frac{500}{340}\approx 1.5\sec $
Therefore Total time $ =t _{1}+t _{2}=10+1.5=11.5\sec . $
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