HW8Sol - a. What is D U of 1.0 kg of water? b. Suppose the...

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1) Estimate the maximum speed of a horse. Assume the horse is 1.8 m tall and 0.5m wide. By definition the power output of a horse is 1hp = 746 W. At constant max speed F net = 0. The propulsion force is balanced by the drag of air resistance D = 0.5 C r Av 2 , where C ≈ 1, r = 1kg/m 3 , A = (1.8m)(.5m) = 0.9m 2 P = 746 W = Fv = Dv = .5Av 3 v = [2(746)/0.9] 1/3 = 12m/s = (27mph) 2) In a hydroelectric dam, water falls 25 m and then spins a turbine to generate electricity.
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Unformatted text preview: a. What is D U of 1.0 kg of water? b. 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 50 MW of electricity? This is a typical value for a small hydroelectric dam. ....
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This note was uploaded on 05/20/2008 for the course PHYS 161 taught by Professor Hammer during the Spring '07 term at Maryland.

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