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$P=1.0 \times 10^3W$

Giancoli 6th Edition, Chapter 6, Problem 67

(1:42)

Chapter 6, Problem 67 is solved.

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Transcript for this Giancoli solution

The power output of these football players is going to be work divided by time and that's going to be the work done against gravity so their weight times the vertical height change of the stairway divided by time so we'll need to express that height in terms of the given length along the stairs that we’re given which is 'D' so the height is the opposite leg of this triangle and we're given theta there as well. So we have height is 'D' sine theta. So we'll make that substitution in to our power formula we have 'MG' times 'D' sine theta over 'T' so we have 95 kilograms times 9.8 Newton's per kilogram times 140 metre long staircase times the sine of 32 degrees that's the angle of inclination of the stairway divided by 66 seconds, it’s how long it takes them to climb it. And this works out to 1.0 times 10 to the 3 watts for the fifth edition the weight of the football players is 105 kilograms, the angle of the stairway is 30 degrees and they climb it in 61 seconds instead of 66. So the fifth edition answer is 1.2 times 10 to the 3 watts.