A student decides to move a box of books into her dormitory room by pulling on a

Question

A student decides to move a box of books into her dormitory room by pulling on a rope attached to the box. She pulls with a force of 152 N at an angle of 28.0

A student decides to move a box of books into her dormitory room by pulling on a rope attached to the box. She pulls with a force of 152 N at an angle of 28.0 degree above the horizontal. The box has a mass of 20.0 kg, and the coefficient of kinetic friction between box and floor is 0.300. (a) Find the acceleration of the box. Your response differs from the correct answer by more than 10%. Double check your calculations. m/s2 (b) The student now starts moving the box up a 10.0 degree incline, keeping her 152 N force directed at 28.0 degree above the line of the incline. If the coefficient of friction is unchanged, what is the new acceleration of the box? m/s2, up the incline

Explanation / Answer

a) sum forces in the y

152*sin(28) + N - 20*9.81 = 0
N=124.8 Newtons

sum forces in the x

152*cos(28) - friction = ma
152*cos(28) - 0.3*124.8 = 20*a

a=4.84 m/s^2

b)

sum forces perp to the slope

152*sin(28) + N - 20*9.81*cos(10) = 0

N = 121.9 N

sum fores parallel

152*cos(28) - 0.3*121.9 - 20*9.81*sin(10) = 20*a

a=3.18 m/s^2

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