A freshwater dolphin sends untrasound sound to locate a prey. If the echo off the prey is received by dolphin `0.12 s` after being send, how far is the prey from the dolphin ?

In the echo method of estimating distnces, a radar signa was sent towards the Mars. If the echo was received after 8 minute 20 second, how far wat the Mars from the earth at that instant?

A submarine that is not moving sends out a sonar sound wave travelling at 2000 m /s is, which reflects off a boat back to the submarine. The sonar crew detects the reflected wave 8 s after it was sent out. How far away is the boat from the submarine ?

A man fires a shot and hears an echo from a cliff after 2 s . He walks 85 m towards the cliff and the echo of a second shot is now heard after 1.4 s . What is the velocity of sound and how far was the man from the cliff when he first heard the echo ?