You and three friends stand at the corners of a square whose sides are 8.0 m lon
ID: 2279662 • Letter: Y
Question
You and three friends stand at the corners of a square whose sides are 8.0 m long in the middle of the gym floor, as shown in the figure (Figure 1) . You take your physics book and push it from one person to the other. The book has a mass of 1.0kg , and the coefficient of kinetic friction between the book and the floor is ?k=0.24.
A)The book slides from you to Beth and then from Beth to Carlos, along the lines connecting these people. What is the work done by friction during this displacement?
B)You slide the book from you to Carlos along the diagonal of the square. What is the work done by friction during this displacement?
C)You slide the book to Kim who then slides it back to you. What is the total work done by friction during this motion of the book?
Explanation / Answer
Part A)
The Work by Friction is found by -uFnd
W = -(2)(.24)(1)(9.8)(8)
W = -37.6 J (If your answer key does not want the negative sign convention, try rntering a positive value
Part B)
The distance is sqrt(8^2 + 8^2)
Distance = 11.31 m
W = -(.24)(1)(9.8)(11.31)
W = -26.6 J
Part B)
There could be two answers to this. The answer should be the same as in Part A since Friction is non-conservative.
The answer should be -37.6 J
However, if they make this into a "Trick" question, since the overall displacement is zero, the work done could be considered zero. Although that could be an answer, it is not correct. It should be -37.6 J
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