Answer:

Explanation:
<u>Gravitational Potential Energy</u>
It's the capacity of an object to do work due to its relative height from a fixed reference point.
It's computed as
GPE=m.g.h
Where m is the mass of the object, h is its height and g is the acceleration of gravity, 
The mass of water is given as

The height above the rocks is h=50 m. Let's compute the GPE


It should be expressed in scientific notation

The GPE at the bottom, where h=0

The change of gravitational potential energy is:


The question is not well presented.
There is ______ shift in sound frequency for observers towards whom the source is approaching.
Answer:
The gap should be filled with an apparent upward
Explanation:
The Doppler effect (also referred to as the Doppler shift) is the difference in frequency of a wave when related to an observer who has a relative movement to the wave source
The Doppler effect can be observed to occur with all types of waves - most notably water waves, sound waves, and light waves
The Doppler effect describes sound as an effect which is produced from a moving source of wave.
According to the Doppler effect;
When the source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching.
There is a lot of help on the internet