"4,000,000,000 J" is the "Potential Energy" of water dropping over "Niagara falls".
Explanation:
The body possess some energy according to the position of the object that is the when an object is placed at a height it stores some energy it is called "Potential Energy".
Formula used to calculate the "Potential Energy" is [tex]m\times g \times h[/tex]
Where, "m" is mass of an object given that 8,000,000 kg, "g" is acceleration due to gravity is [tex]10 m/s^2[/tex] and "h" is height of the object is 50 m.
Substitute the given values in the formula,
Potential energy = [tex]8,000,000\times10\times50[/tex]
Potential energy = 4,000,000,000 J
