A box is placed on a rough plane inclined at above the horizontal
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 6.0kg box is placed on a rough plane inclined at 20∘ above the horizontal. The coefficient of kinetic friction between the box and the plane is 0.25. A worker pulls on the box with a constant 40N force directed horizontally (parallel to the ground, not along the plane) as shown in the description. Immediately after the box is set in motion, it moves up the plane.
Neglect air resistance.
(a) Resolve the worker’s 40N horizontal force into components parallel and perpendicular to the plane.
(b) Determine the magnitude of the normal force exerted by the plane on the box while it is moving.
(c) Calculate the magnitude of the net force acting parallel to the plane on the box.
(d) Determine the magnitude and direction (up or down the plane) of the acceleration of the box just after it begins to move.