Statics with Friction

From handout:

Problem 1: Fn = 400 N, Fk = 173.2 N, mu = .433
Problem 2: Fn = 250 N, Fk = 173.2 N, mu = .693

Systems Problem (We will talk about this first thing tomorrow. There are some subtle points to discuss on how to do these types of problems.

Mass M = mu*M = 2 kg

Book Problems:
Q22. Since friction force is proportional to the normal force, putting a force against the box and perpendicular to the wall increases the normal force, which then increases the friction force.

Problems:
38. Friction force = 102.9 N. If mu = 0, there wouldn't be any friction force, and the only magnitude of F that could lead to constant velocity across the floor would be zero!

43. 6.667 kg

59. You should obtain that tan(phi) = mu. Thus phi = arc_tan(0.6) = 31.0 degrees.

63.
T = mg = 26.46 N,
Fk = mg - mg*sin(theta) = mu * Fn
Fn = mg cos(theta)

mu = 0.637

Problem 54. The clown must pull with a force of 308.3 N.