Question

The velocity of air in a planet is 500m/s. What should be the minimum distance between the source of sound and the obstacle to hear an echo?a) 20b) 25c) 50d) 17​

Answer 1

Answer:

b) 25m

Explanation:

v = d/t

as minimum time to hear an echo is 0.1 seconds,

500 = d/0.1

d = 500 * 0.1

d = 50m

As this includes going and coming back of the wave, the distance from the object to the person should be d/2 as it takes equal amounts of time to go and return.

d/2 = 50/2

= 25m