Question

The pitch of the whistle of an engine appears to rise to 1.2 times the original value when it approaches a stationary observer calculate the speed of the engine

Answer 1

Hey dear,

◆ Answer-
v' = 56.67 m/s

◆ Explaination-
As pitch of the whistle depends on apparent frequency.
f' = 1.2 f

Let v' be speed of engine.

According to Doppler effect in sound,
f' = f (v / v-v')
1.2 f = f (340 / 340-v')
408 - 1.2v' = 340
1.2v' = 68
v' = 56.67 m/s

Therefore, speed of the engine is 56.67 m/s.

Hope it helps...

Answer 2

Answer:

55 m/s

Explanation:

and should be 55m/s