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posted by  eddy143 on 11/5/2009 3:23:42 AM  |  status: Live  |  Earned Karma: 0

phy101 last question help plz

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N/A N/A N/A N/A 11/10/2009 at 7:00:00 PM
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A student with a mass of 50.0 kg runs up three flights of stairs in 10.0 sec. The student has gone a vertical distance of 8.0 m. Determine the amount of work done by the student to elevate his body to this height. Assume that her speed is constant.               
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posted by Tours2009 on 11/11/2009 12:30:17 AM  |  status: Live
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The student weighs 490 N (Fgrav= 50 kg * 9.8 m/s/s).

To lift a 490-Newton person at constant speed, 490 N of force must be applied to it (Newton's laws). The force is up, the displacement is up, and so the angle theta in the work equation is 0 degrees. Thus,

W = (490 N) * (8 m) * cos (0 degrees) = 3920 Joules
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