A) 80 m
B) 85 m
C) 75 m
D) 70 m
Correct Answer: B
Solution :
Let the distance be ?d?. The time taken for one complete oscillation (i.e., the time period) by a seconds pendulum = 2s \[\therefore \]The time taken for it to move from the mean to the extreme position\[=\frac{1}{4}\times 2s=0.5s\] \[\therefore \]speed of sound\[=340\text{ }m{{s}^{1}}.\] Distance travelled by sound before the echo is heard = 2d \[2d=speed\times time\] \[2d=340\times 0.5\]\[\Rightarrow \]\[d=85\text{ }m\]You need to login to perform this action.
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