room by puling on a rope attached to the bew, She mass of 20.0 kg, and the coeff
ID: 1659472 • Letter: R
Question
room by puling on a rope attached to the bew, She mass of 20.0 kg, and the coefficient of kinetic frictien between box and foor 0 300.(Inicate the dretmen with the sgn of )Find the acceleration oren ben. (Assume that eheraxis is to the ne ted the .rae..upalang oe e.) direction Your respanse offers siscanly from the comect ner Rework youlton rm se (b) The student now starts moving the box up a 1o.0 indline, keeping her 30 2 Nae rected at 29.o aoove the oe of the incioe acceleration of the box? (Assume thar the w-axis is along the indine and e yaxs is upeards and perpendicular to the incine) the cfest of friction wechanged, atat t magnitude m/sExplanation / Answer
a) sigma Fx = ma
70.2 N * cos 29 – f = ma
61.4 N – f = ma
sigma Fy = 0
FN + 70.2 sin 29 – (20 * 9.8) = 0
FN = 161.97 N
f = mu * FN = 0.300 * 161.97 = 48.59 N
a = (61.4 – 48.59) / 20 = 0.64 m/s2
direction = 0 deg
b) sigma Fx = ma
70.2 * cos 29 – f – mg sin 10 = m a
61.4 – 34 N – f = (20) a
27.4 N – f = 20 a ------(2)
sigma Fy = 0
FN + 70.2 sin 29 – mg cos 10.00 = 0
FN = 159 N
f = mu * FN = 0.300 * 159 = 47.7 N
substitute in equation 2
27.4 N – 47.7 = 20 a
a = -1.01 m/s2
direction = 180 deg
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