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Question 1.27: Calorie (energy) and horsepower (power) are two non-SI units...

Calorie (energy) and horsepower (power) are two non-SI units that you might see on occasion.

A) Death Valley National Park contains a region that is rich in borax. In the 19th century, borax was harvested and shipped on wagons pulled by 20-mule teams. Estimate the power driving these wagons, in Watts, using the assumption that a 20-mule team provides 20 horsepower.
B) A stove produces 10,000 calories of heat. What is this in Joules? In BTU?
C) An engine produces 100,000 calories of work in 1 minute. What is the power of the engine in horsepower, and in Watts?

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A) \,(20\,\rm Mulepower )\left(\frac{1 \,\mathrm{hp}}{1 \text { Mulepower }}\right)\left(\frac{1 \mathrm{~W}}{0.001341 \,\mathrm{hp}}\right)=\mathbf{1 4 9 1 4 . 2 \, W }

B)

\begin{gathered}(10000 \,\mathrm{cal})\left(\frac{1 \mathrm{J}}{0.23901 \,\mathrm{cal}}\right)=\mathbf{4 1 8 3 9 . 2 \,J }\\(10,000 \,\mathrm{cal})\left(\frac{0.0009486 \,\mathrm{BTU}}{0.23901 \,\mathrm{cal}}\right)=\bf 39.7\,BTU\end{gathered}

C)

\begin{gathered}\left(\frac{100,000 \,\mathrm{cal}}{1 \mathrm{~min}}\right)\left(\frac{1 \mathrm{~J}}{0.23901 \,\mathrm{cal}}\right)\left(\frac{1 \mathrm{~min}}{60 \,\mathrm{sec}}\right)\left(\frac{1 \mathrm{~W}}{1 \frac{\mathrm{J}}{\,\mathrm{sec}}}\right)=\bf 6973 \,W\\\left(\frac{100,000 \,\mathrm{cal}}{1 \mathrm{~min}}\right)\left(\frac{1 \mathrm{~J}}{0.23901 \mathrm{cal}}\right)\left(\frac{1 \mathrm{~min}}{60 \mathrm{sec}}\right)\left(\frac{1 \mathrm{~W}}{1 \frac{\mathrm{J}}{\mathrm{sec}}}\right)\left(\frac{0.001341 \,\mathrm{Hp}}{1 \mathrm{~W}}\right)=\bf 9.35 \, Hp\end{gathered}

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