:3 Apps Report A P MyCUlnfo Desire2Learn OIT Labs Page Correct, computer gets: 3

Question

:3 Apps Report A P MyCUlnfo Desire2Learn OIT Labs Page Correct, computer gets: 3.12E+04 W Hint: There are several ways to solve this problem. You'll have to remember the old Ch. 4 techniques for dealing with "objects on an slope": in fact a force diagram will be "needed* to find the tension in the cable the cable requires that you find the FORCE of the cable (which is another name for the tension in we cable). the work done by 10.(1pt] A 54.60 kg keg of beer slides upright down a 2.60 m long plank leading from the back of a truck 1.12 m high to the ground. The coefficient of kinetic friction, muk-0.20. Determine the amount of work done on the keg by gravity. Correat, computer gets: 5.99E+02 N*m Hint: Look at section 6.3 in Cutnell. You don't necessarily have to use every number or quantity given in the problem statement. Think about signs, work can be + or- (What is it here?) 11.[1pt] In the previous problem, what is the total work done by friction on the keg? Submit All Answers Last Answer: 251.14 Answer: Incorrect, tries 2/6. uires finding the normal force.. Think about signs, work can be + or -. (What is it here?)

Explanation / Answer

The normal force i:

N = mgcos(th) , where th = ramp angle = 25.5 degrees

Thus:

N = 54.6*9.8*cos25.5 = 483N

Thus, friction f = uN = 0.20*483 = 96.59N

Thus work done by friction is:

Wf = -fd = - 96.59*2.6 = -251.14J

[You missed on the negative sign which will be there since friction and displacement are in opposite direction]

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