Physics (10th Edition)

Published by Wiley
ISBN 10: 1118486897
ISBN 13: 978-1-11848-689-4

Chapter 6 - Work and Energy - Problems - Page 171: 80


The potential energy of the child will increase by $444J$.

Work Step by Step

We have $$\Delta PE=mg(h_f-h_0)$$ The shape of the staircase is not important, as $PE$ is a conservative force. We only care about the height of the staircase, which is the same for the 2 staircases here. - For the adult climbing the staircase, $$\Delta PE_{adult}=m_{adult}g(h_f-h_0)$$ - For the child climbing the staircase, $$\Delta PE_{child}=m_{child}g(h_f-h_0)$$ We have $$\frac{\Delta PE_{child}}{\Delta PE_{adult}}=\frac{m_{child}g(h_f-h_0)}{m_{adult}g(h_f-h_0)}=\frac{m_{child}}{m_{adult}}=0.222$$ $$\Delta PE_{child}=0.222\Delta PE_{adult}=444J$$
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