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posted by  100x35 on 7/3/2009 10:57:05 AM  |  status: Live  |  Earned Karma: 25

Mechanics Dynamics; Force, Mass, and Acceleration...will rate

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Question Details:
The crate has a mass of 120 kg, and the coefficients of friction between it and the sloping dock are μs = 0.6 and μk = 0.5.
(a) What tension must the winch exert on the cable to start the stationary crate sliding up the dock ?
(b) If the tention is maintained at the value determined in part (a) what is the magnitude of the crate's velocity when it has moved 2 m up the dock ?
                                                                   
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posted by rooya(MNK) on 7/4/2009 8:20:40 AM  |  status: Live
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Response Details:
 

m=120kg

W= 120*9.81N

μs = 0.6 ; μk = 0.5

Let  "T" be the tension in the string

F= Frictional force

ΣFy = 0

F = μsN

N=Wcosθ

N=120*9.81cos30

N=1019.48N

F=0.6*1019.48

F=611.69N

ΣFx = 0

T- Wsinθ -F =0

T = Wsinθ + F

T = 120*9.81sin30 + 611.69

T = 1200.29N
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