Question

a car is moving with speed 20 metre per second towards a hill it sound a home then when it is at a distance of 1 kilometre from the hill speed of sound is 300 metre per second find the time after which driver of the car hear the Eco of horn

Answer 1

Let's suppose echo is heard after t seconds. So distance travelled by sound in t seconds= speed × t= 300t.

distance travelled by car in t seconds= speed×t= 20t.

overall distance travelled by sound and car= 320t.

distance that needs to be covered by sound for echo= 1000(1km)×2= 2000m.

So time (t)=> 2000= 320t

t=2000÷320= 6.125 seconds.

Hope it helped.