Water flows from a reservoir at the rate of 3000 kg/min, to a turbine 120 m below. If the efficiency of the turbine is 80 percent, compute the power output of the turbine. Neglect friction in the pipe and the small KE of the water leaving the turbine. Don't forget that it's only 80 percent efficiet.

Compute the power output of a machine that lifts a 500 kg crate through a height of 20m in a time of 60s

An engine expends 40hp in propelling a car along a level track at a constant speed of 15m/s. How large is the total retarding force acting on the car? Remember that 1 hp= 745.7 W

A 1000 kg auto travels up a 3 percent grade at 20 m/s find the cruising power required, neglecting friction

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Hint: every one of these can be solved by using the fact that power = work per unit time, which also equals force times velocity.