A) \[\frac{v}{\sqrt{2}}\]
B) \[\frac{v}{3}\]
C) \[\frac{v}{4}\]
D) \[\frac{v}{2}\]
Correct Answer: B
Solution :
| When the sound is reflected from the cliff, it approaches the driver of the car. Therefore, the driver acts as an observer and both the source(car) and observer are moving. |
| Hence, apparent frequency heard by the observer (driver) is given by |
| \[f'=f\left( \frac{v+{{v}_{o}}}{v-{{v}_{s}}} \right)\] (i) |
| where\[v=\] velocity of sound, |
| \[{{v}_{o}}=\] velocity of car \[={{v}_{s}}\] |
| Thus, Eq. (i) becomes |
| \[\therefore \] \[2f=f\left( \frac{v+{{v}_{o}}}{v-{{v}_{o}}} \right)\] |
| or \[2v-2{{v}_{o}}=v+{{v}_{o}}\] |
| or \[3{{v}_{o}}=v\] |
| or \[{{v}_{o}}=\frac{v}{3}\] |
You need to login to perform this action.
You will be redirected in
3 sec
