Two cars A and B are moving away from each other in opposite directions. Both the cars are moving with a speed of `20 ms^(-1)` with respect to the ground. If an observer in car A detects a frequency 2000 Hz of the sound coming from car B, what is the natural frequency of the sound source in car B? (Speed of sound in air =`340 ms^(-1)`)

Options

A. 2060Hz
B. 2300Hz
C. 2250Hz
D. 2150Hz

Answer

C

Explanation

`f = f_(0)[(v-v_(0))/(v + v_(0))]`
When moving away from each other
`2000 = f_(0)[(340 - 20)/(340 + 20)], f_(0)= 2250 Hz`