A fixed volume is where either a solid or liquid has a volume that is constant under the same pressure and temperature. A gas cannot have a fixed volume because it changes by itself without any human interaction.
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The mechanical energy in the falling water is used to spin the generator, and gets transformed into electrical energy. That's the first choice on the list.
Answer:
Mass and height
Explanation:
Gravitational potential energy is energy an object possesses because of its position in a gravitational field. The most common use of gravitational potential energy is for an object near the surface of the Earth where the gravitational acceleration can be assumed to be constant at about 
Which is represented as;

stands for gravitational potantial energy,
m stands for mass of object,
g is the gravitational constant and
h is the height.
Here we see that mass of object and height is directly proportional to the gravitational potential energy.
That means increasing in mass and height will result in increasing gravitational potential energy.
A vacuum is an electrical motor and<span> which it converts electrical energy into mechanical energy.
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