A block with a mass 4.0 kg is held in equilibrium on an incline of angle θ = 42° by a horizontal force F.

a)Find the magnitude of the normal force.
b) Find the magnitude of F. (Ignore friction.)

1 answer

a) The applied horizontal force is balanced by the weight and the normal force applied to the block by the incline.

Let the normal force be Fn.

Fn = M g cos42 + F sin42
F cos42 = M g sin42

Solve for Fn

Fn = M g (cos42 + sin42*tan42) = 52.7 N
W = 39.2 N
b) F = 35.3 N