If a student measures that the block begins to move at an

Question

A block is resting on a wooden plank. There is a hinge on one end of the plank which allows the other end to be lifted to create an angle, θ, with respect to the horizontal as shown in the figure. The coefficient of static friction between the block and the plank is μ_s.

Part (a) Please select the correct Free Body Diagram, where F_g is the force due to gravity,F_N is the normal force, and F_s is the static friction force.

Part (b) The angle θ is slowly increased. Write an expression for the angle at which the block begins to move in terms of θ_s.

Part (c) If a student measures that the block begins to move at an angle of θ = 31^o, what is the numerical value of the coefficient of static friction, μ_s?