question_answer

The echo of a gunshot is heard 8 sec. after the gun is fired. How far from him is the surface that reflects the sound (velocity of sound in air = 350 m/s) [JIPMER 1999]

A)            1400 m                                    

B)            2800 m

C)            700 m                                      

D)            350 m

Correct Answer: A

Solution :

            Suppose the distance between shooter and reflecting surface is d. Hence time interval for hearing echo is \[t=\frac{2d}{v}\] Þ \[8=\frac{2d}{350}\] Þ \[d=1400\,m\].