Question

A car move towards a hill and sound its horn when it is at a distance of 1 km drom the hill the echo is heared after 5 second find the speed of car if speed of sound is 340 m/s

Answer 1

Answer:

t1 = 1000 / 340 = 2.94 sec     time for sound to reach hill

t2 = (1000 - s) / 340   where s is distance car travels and t2 time for sound to reach the car

t1 + t2 = 5 = (2000 - s) / 340

1700 = 2000 - s

s = 300    the distance car travels

So v = 300 / 5 = 60 m/s     (134 mph?)

As a check the total distance the sound travels is

5 * 340  = 1700 m

So the car must travel 300 m in 5 sec