Answer: the water level would rise since the pebble displaces minimal water compared to the boat.
Explanation:..........
Answer:
The frequency of the waves depends on the distance between wave fronts - considering a front as a maximum disturbance of the wave
(Consider the waves emitted by an organ pipe: condensation and rarefactions)
The waves themselves are a fixed distance apart -
as one moves towards the source the waves received will be closer together (higher frequency)
So if the frequency received increases, the distance between the source and the observer must be decreasing
