Physics

How long does it take a 19 kW steam engine to do 6.8x10^7 of work?

I have no idea how to solve this... Would someone please help?

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  1. well 1 W = J/s So, 19 kW is 19000 J/s. But you want to find time, so you want to have seconds in the denominator, you you would multiply the inverse of the watts times the amount of work.

    so (1 sec/19000 J) * (6.8 X 10^7 J)

    Joules should cancel out with joules and you should be left with seconds.

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  2. power = 19*10^3 Watts = 19*10^3 Joules/s

    work = power * time
    6.9*10^7 J = 19 * 10^3 J/s * t
    so
    t = 6.9*10^7 / 19*10^3

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  3. You omitted the dimensions of the work in your quetion. We assume it is in Joules

    I'm pretty sure Damon meant 6.8 instead of 6.9 in his number for the work done. With that change, both previous answers agree.
    t = 3579 s

    With only 2 significant figures in the input numbers, the answer should be stated as 3600 s or one hour.

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