Question

5. Guns are fired from a city at intervals of 10 minutes, and a train was approaching
the city with a speed of 72 km/hour. If sound travels 380 metres per second, at what
interval of time the passenger of the train hears two successive sounds ?​

Answer 1

Answer:

= 9min 30sec

Step-by-step explanation:

velocity of train = 72 km/h = 72*5/18 m/s = 20 m/s

the second bullet is fired after 10 min of the first bullet. Hence the first bullet sound has travelled a distance of 10*60*380 (=228000) meters before the second sound starts. this is the distance between any two sound pulses.

Now this distance is coverd by the train + sound. The relative velocity = 380+20 = 400m/s.

Hence the train will hear the second sound after a time of t = distance/speed = 228000/400 = 570 seconds.

= 9min 30sec