A wooden block of mass is placed on a fixed rough plane that is inclined at an angle…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A wooden block of mass m is placed on a fixed rough plane that is inclined at an angle θ above the horizontal. The block is initially at rest and remains at rest. (Assume that the coefficient of static friction is large enough to prevent motion.) Throughout your response, use clear reasoning that refers explicitly to forces acting on the block.
(a) Draw a free-body diagram for the block and list every force acting on the block, naming each force and indicating the object that exerts it.
(b) Resolve the gravitational force into components that are parallel to and perpendicular to the surface. Write each component symbolically in terms of mg and θ.
(c) Explain, without performing any numerical calculation, why choosing the coordinate axes to lie parallel and perpendicular to the surface simplifies the application of Newton’s second law for an object on an incline.