An electric motor consumes 2 kw electricity and is 95% efficient in converting e

Question

An electric motor consumes 2 kw electricity and is 95% efficient in converting electricity to kinetic energy. The motor is used to lift a 100 kg box from the ground level to the 3rd story of a building that is 10 m high. Calculate the minimum time required for this job. I. At a certain location the air density is 1.2 kg m' and wind is blowing steadily at 12 m/s. A wind- turbine with a blade diameter of 50 m and an efficiency of 40% converts the wind energy to electrical power. (a) Determine the power generation rate of the turbine. (b) If the generated electricity is delivered at 40 kV, what would be the maximum current, ? 2. A heat engine is a device that operates between a hot heat source and a cold heat sink (or multiple heat sources/sinks) and converts thermal energy to work. For the heat engine shown below, (a) find the rate of work production, and (b) find the efficiency of the engine 3. n100 w iw Heat Engine

Explanation / Answer

1) Energy required by motor = mgh/efficiency

Power*time = 100*9.8*10/0.95

Time = ( 100*9.8*10/0.95)/2000

= 5.16 s answer

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