Physics (AS & A Level) · May / June 2019 · Paper 11 · Question 26

A toy motorboat moving with constant velocity v vibrates up and down on the surface of a pond. This causes the boat to act as a source of circular water waves of frequency 2.0 Hz. The speed of the waves is 1.5 m s–1. A man, standing at the edge of the pond, observes that the waves from the boat approach him with a frequency of 3.0 Hz. The formula for Doppler effect calculations with sound waves may also be used for water waves. What is a possible value of v?

1. A0.50 m s–1, directly away from the man
2. B0.50 m s–1, directly towards the man
3. C0.75 m s–1, directly away from the man
4. D0.75 m s–1, directly towards the man

As printed in the paper