Question

A stationary source S generates circular outgoing waves on a lake. The wave speed is 5.0 m/s and the crest-to-crest distance is 2.0 m. A person in a motorboat heads directly toward S at 3.0 m/s. To this person, the frequency of these waves is:

Answer 1

Answer:4 Hz

Explanation:

Speed of wave $v=5 m/s$

crest to crest distance $\lambda =2 m$

velocity of observer $v_0=3 m/s$

actual frequency $f=\frac{velocity}{\lambda }$

$f=\frac{5}{2}=2.5 Hz$

Apparent frequency $f'=f(\frac{v+v_0}{v})$

$f'=2.5\times \frac{5+3}{5}$

$f'=4 Hz$