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 100.0 N at an angle of 25.0° above the horizontal. The box has a mass of 25.0 kg, and the coefficient of kinetic friction between box and floor is 0.300.

Question

(a) Find the acceleration of the box.

(b) The student now pulls the moving box up a 10.0° incline, keeping her 100.0 N force directed at 25.0° above the line of the incline. If the coefficient of friction is unchanged, what is the new acceleration of the box?

Answer 1

break up the rope force into two components. The vertical component reduces the normal force (mg-verticalforce), so friction is reduced.

Then use the horizontal component of force to set equal to ma + frictionforce.