Work, Energy, and Power in Humans: [IMAGE] The awe-inspiring Great Pyramid of Cheops was built mo...

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The awe-inspiring Great Pyramid of Cheops was built more than 4500 years ago. Its square base, originally 230 m on a side, covered 13.1 acres, and it was 146 m high, with a mass of about 7 x 1 0 9 kg . (The pyramid's dimensions are slightly different today due to quarrying and some sagging.) Historians estimate that 20,000 workers spent 20 years to construct it, working 12-hour days, 330 days per year. Gravitational potential energy stored in the pyramid is 2.50 x 1 0 12 J. Only a fraction of the workers lifted blocks; most were involved in support services such as building ramps (see the figure above), bringing food and water, and hauling blocks to the site. Calculate the efficiency of the workers who did the lifting, assuming there were 1000 of them and they consumed food energy at the rate of 300 kcal/h. What does your answer imply about how much of their work went into block-lifting, versus how much work went into friction and lifting and lowering their own bodies?

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This question is available under a CC BY license. Attribution: Rice University. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution 3.0 Unported License.
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