How do I do Physics problems like this?

Question

13.  A whistle of frequency 540 Hz moves in a circle of radius 60 cm at an angular speed of 15 rad/s.  What is the highest frequency that an observer a long distance away might hear?

or...

14.  A whistle of frequency 540 Hz moves in a circle of radius 60 cm at an angular speed of 15 rad/s.  What is the lowest frequency that an observer a long distance away might hear?

I'm thinking it is probably pretty simple, but I have no idea where to start. Thanks!

Anonymous · Accepted Answer

Use the Doppler Effect. The highest frequency will occur when the source is moving toward that observer and the lowest frequency will occur when the source is moving away from the observer. Also use velocity=(angular velocity * Radius).

Highest freq -> f'=f/(1-(velocity of source/343))

Lowest freq-> f'=f/(1+(velocity of source/343))

Highest freq -> f'=f/(1-(velocity of source/343))
Lowest freq->  f'=f/(1+(velocity of source/343))

How do I do Physics problems like this?

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