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 78.6 N at an angle of 26.0° above the horizontal. The box has a mass of 21.0 kg, and the coefficient of kinetic friction between box and floor is 0.300. (Indicate the direction with the sign of your answer.)

(a) Find the acceleration of the box. (Assume that the +x-axis is to the right and the +y-axis is up along the page.)

I have found the magnitude but I am having some trouble finding the direction.

Magnitude = .916 m/s^2

Direction = ?

(b) The student now starts moving the box up a 10.0° incline, keeping her 78.6 N force directed at 26.0° above the line of the incline. If the coefficient of friction is unchanged, what is the new acceleration of the box? (Assume that the +x-axis is along the incline and the +y-axis is upwards and perpendicular to the incline.)

I have also found the magnitude of this question, but again am having trouble finding the direction.

Magnitude = .740 m/s^2

Direction = ?

Explanation / Answer

In both the cases, the acceleration is along the positive x-axis. The cosine component of the force is responsible for the acceleration in both the cases.

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