A 193 kg curtain needs to e raised 7.5 m, at constant speed, in as close to 5.0 s as possible. The power ratings for three motors are listed

Question

A 193 kg curtain needs to e raised 7.5 m, at constant speed, in as close to 5.0 s as possible. The power ratings for three motors are listed as 1.0 kW, 3.5 kW, and 5.5 kW. Which motor is best for the job?

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Trúc Chi 3 years 2021-08-09T17:17:59+00:00 1 Answers 207 views 0

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    2021-08-09T17:19:37+00:00
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    Answer:

    best motor for above purpose is 3.5 kW

    Explanation:

    As we know that power is defined as the rate of work done

    Here we have to raise the curtain so work is done against gravity

    So we have

    W = mgH

    here we know

    m = 193 kg

    g = 9.8 m/s^2

    Now we have

    W = (193)(9.8)(7.5)

    W = 14185.5 J

    now power used in it

    P = \frac{14185.5}{5}

    P = 2.8 kW

    So best motor for above purpose is 3.5 kW

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