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Power Chapter 5, Section 4. Power. Power is the rate at which energy is transferred. Ex. The rate at which a light bulb transfers energy depends on its wattage. Power can be measured in either watts (W) or in horsepower (hp). 1 W = 1 J/s. 1 hp = 746 watts. Mathematically expressed as:.
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Power Poweris the rate at which energy is transferred. Ex. The rate at which a light bulb transfers energy depends on its wattage.
Power can be measured in either watts (W) or in horsepower (hp). 1 W = 1 J/s 1 hp = 746 watts Mathematically expressed as: P = W/Δt P = Fν P = maν P = Fd/Δt
Sample Problem A 193 kg curtain needs to be raised 7.5 m at a constant speed in as close to as 5.0 s as possible. Which of the following motors is the best for the job: 1.5 kW, 3.5 kW, or the 5.5 kW motor. g = 9.81 m/s² m = 193 kg Δt = 5.0 s d = 7.5 m P = W/Δt = Fd/Δt = mad/Δt P = (193 kg) (9.81 m/s²) (7.5 m) / 5.0 s P ≈ 2.8 x 10³ W or 2.8 kW