What is the beat frequency for a cyclist ringing a bell towards a wall?

[Joy Wong]

Homework Statement

A cyclist with a bell ringing with a frequency of 659.7 Hz drives towards a wall with a speed of 8.15 ms-1. Just before colliding with the wall the cyclist hears beats, due to the bell itself and the reflection of the sound from the wall. What is the frequency of beats detected by the observer? Assume that the velocity of sound in air is 343 ms-1.[/B]

Homework Equations

[/B]

The Attempt at a Solution

 

[ehild]

Welcome to PF! According to the forum rules, you have to show some attempt for solving the problem. You also have to write the equations relevant.
As example see the similar thread https://www.physicsforums.com/threads/doppler-effect-and-concept-of-beat-problem.817004/

 

[Joy Wong]

Ok,thanks