(6%) Problem 12. A child of mass m = 19 kg slides down a slide of height h 2.3 m
ID: 2031880 • Letter: #
Question
(6%) Problem 12. A child of mass m = 19 kg slides down a slide of height h 2.3 m without friction. Let gravitational potential energy be zero at ground level Randomized Variables m-19 kg h- 2.3 m 33% Part (a) Write an expression for the child's total mechanical energy, E. at the top of the slide Grade Summary Deductions Potential 0% 100% Submissions Attempts remaining: 7 (0% per attempt) detailed view Inn END CE Submit Hint I give up! Hints: 2% deduction per hint. Hints remaining: 3 Feedback: 2% deduction per feedback Calculate the change in the child's potential energy, ??? joules, fromn the top to the bottom of the slide at ground level (ie 33% Part b U-Uground-top 33% Part (c) what is the child's final speed, yin ms?Explanation / Answer
a) potential energy = m g h
kinetic energy = 1/2 m vi2 = 0
child's total mechanical energy = m g h
b) change in potential energy = - m g h
= - 19 * 9.8 * 2.3
= - 428.26 J
c) Ui + Uf = Ki + Kf
1/2 m vf2 = m g h
vf2 = 2 g h
vf2 = 2 * 9.8 * 2.3
child's final speed vf = 6.71 m/s
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