Question

A person riding on a bus hears the horn of a car that the bus is approaching. After the bus passes the car and is traveling away from it, the bus rider hears the car horn again. Choose the best description of the new sound heard by the bus rider.
A. The car horn will sound the same, not higher or lower than it did before.
B. The car horn will sound higher in frequency than it did before.
C. The car horn will sound lower in frequency than it did before.

Answer 1

Answer:

option (c)

Explanation:

According to the doppler's effect, the frequency of sound decreases.

If there is a relative motion between the source and the observer, the frequency of sound changes apparently.

the formula of the doppler effect is given by

$f' =\frac{v-v_{o}}{v}}f$

where, f is the real frequency, v be the speed of sound, vo be the speed of the observer, here, the bus is the observer.

So, the value of f' < f