Tinku dropped a stone into a very deep well. He hears the sound 6.53 s after he dropped the stone. Find the depth of the well. Take acceleration due to gravity, g=10 ms−2 and vsound=340 ms−1.
180 m
Given,
initial velocity, u=0
acceleration due to gravity, g=10 ms−2
speed of sound, vsound=340 ms−1
T1 = time taken by the stone to reach depth D when it is thrown
T2 = time taken by sound to reach the surface
From second equation of motion, we have, s=ut+12at2
D=12×10×T21
T1 = √2×D10 = √D5
We know, time=distancespeed
⇒ T2 = D340
Total time, T1+T2 = √D5 + D340=6.53
On solving we get, D=180 m.