magnitude of static friction force on brick-need help!

Question

A 1.90 kg brick is placed on a ramp with a 32.0' slope. The coefficient of static friction is 0.72. What is the magnitude of the static friction force acting on the brick?

Answer 1

The maximum static friction possible is μ_smg cos(32°) = (0.72)(1.9)(9.8)cos(32°) ≈ 11.4 N

The gravitational force parallel to the incline is mg sin(32°) = (1.9)(9.8)sin(32°) ≈ 9.4 N which is not enough force to overcome static friction.

Since the brick is not moving, the magnitude of the static friction force acting on the brick is the same as that of the gravitational force parallel to the incline.

Answer

9.4 N