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2018 Main Menu Contents Grades Syllabus Course Contents »... » Week 5 Homework set Timer Notes Info Evaluate 4e Feedback-Print Dragging a crate Due in 11 hours, 19 minutes By pulling a on rope attached to a crate of mass 99.0 kg, the crate is dragged across a floor. Let the coefficient of static friction between the crate and the floor be 0.860 and the angle between the rope and horizontal is 20.1. Find the minimum force required to move the crate Submit Answer Tries 0/10 At a later time the crate is now dragged with this same force, and has already started moving, on a wet floor where the kinetic friction coefficient is 0.516. What is the magnitude of the acceleration of the crate? Submit Answer Tries 0/10 View Chronological View rk NE Export new NEW Jake Cirino Reply (Wed Feb 14 11:58:14 am 2018 (EST)) I literally can't find the answer to the first part, I have tried multiple numbers and its just flatout wrong I'm trving Fmin u*ma, which would aive

Explanation / Answer

in vertical,

N + F sin20.1 - (99 x 9.8) = 0

N = 970.2 - F sin20.1 .... (i)

f_max = us N = 834.37 - 0.860 F sin20.1

in horizontal, Fnet = Fcos20.1 - f_max = 0

F ( cos20.1 + 0.860 sin20.1) = 834.37

F = 675.8 N .....Ans

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now kinetic frictin will act,

fk = uk N = 0.516 (970.2 - 675.8 sin20.1 )

fk = 380.8 N

Fnet = 675.8cos20.1 - 380.8 = 99 a

a = 2.56 m/s^2

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