Open-Response Homework Problem 16.2 A man sitting on a 1.4iii ledge carefully lo
ID: 1323653 • Letter: O
Question
Open-Response Homework Problem 16.2 A man sitting on a 1.4iii ledge carefully lowers a 4kg object with a rope so that it comes to a stop when it reaches the ground. Let your system be the Earth and the object (but not the man). For the time between when the object starts downward, at a speed of 1 m/s. and when it reaches the ground (with zero velocity), answer the following questions: (a)[5 Pt(s) Has the man done any work on the object? Explain. (b)[3 Pt(s) What external forces are acting on the object as it falls? (recall that the Earth is in the system) (c)[8 pt(s) what are the changes in the kinetic energy and potential energy of the system? What is the work done?Explanation / Answer
1. Yes
2. Normal force and force applied by man
3. net work DOne = Chnage in KE + Change in PE
Change in KE = 0.5 * 4 * 1*1 - 0 = 2J
Change in PE = 4 * 9.8 * 1.4 = 54.88 J
net work done = 54.88-2 = 52.88 J
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