Question

A person stands between two cliffs at distance d1 and d2 respectively. He claps every 2 seconds . The third clap coincide with the echo of first clap. If the speed of the sound is 360 m/sec, find d2-d1

Answer 1

I think you are right that man isn't at the center of the cliff , and what I have thought that :  

if the distance between the cliffs is 1020m and if man was at 340m to the right of 1st cliff, then let wave moving left towards 1st cliff be A  

& the other moving to right be B .

Now A should move 340m to reach 1st cliff taking 1 second ; and come back to man after 2 seconds  

while the wave B has to travel 680m to reach the 2nd cliff, so, when A wave was at the place where man was standing the B wave was at other cliff at 2 sec.

Now again as the A wave is moving towards right now it has to cover 680m to reach 2nd cliff . While B wave would also need to travel 680 m to reach man , so it takes 2 second and so on.