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In a hydroelectric dam, water falls 27.0 m and then spins a turbine to generate electricity. You may want to review (Pages 234 - 238) .

Part A What is ΔU of 1.0 kg of water? Express your answer with the appropriate units.

Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 54.0 MW of electricity? This is a typical value for a small hydroelectric dam.

Given,

Initial height of water

Mass of water

a) To find change in the potential energy of water.

Here, - mass of water and - intial height of water and final height of water is

Now substitute , and

This sign shows that, when water falls down it loses it's potential energy.