A hydroelectric power plant has a water reservoir with an area of ​​20 km2. The water level in the water reservoir is regulated
as required. The highest regulated water level is 635 m above sea level. while the lowest regulated
the water level is 510 m. This means that the water reservoir cannot have a higher water level than 635 m above sea level.
or a lower water level than 510 m.
Imagine that the water reservoir is a rectangular prism and that the water reservoir is completely full, i.e. that
the water level is 635 m above sea level. At the same time, the need for electricity is great and the hydropower plant will
produce as much electricity as possible without lowering the water level below 510 m.

a) How much water (volume) is available for power generation?

We can calculate the potential energy of the water using the formula for potential energy
= ℎ
where E is the potential energy, m is the mass of the water, g is the gravitational constant and h is
the drop height.
b) Which factors are constant and which are variables?

c) Average drop height is 500 m. How much potential energy is available for