Question

Two 10 kilogram boxes are connected by a massless string that passes over a massless frictionless pulley as shown above. The boxes remain at rest, with the one on the right hanging vertically and the one on the left 2.0 meters from the bottom of an inclined plane that makes an angle of 60° with the horizontal. The coefficients of kinetic friction and static friction between the Ieft hand box and the plane are 0.15 and 0.30, respectively. You may use g = 10 m/s2, sin 60° = 0.87, and cos 60° = 0.50

Answer 1

Determine the magnitude of the frictional force acting on the box on the plane.

Answer 2

By using g=10 m/s^2, I know that T=100N.

I was thinking of using the formula: f =F-umgsin(60), but the solutions I find online say that I should get rid of the u. Why?

Answer 3

Wait, I just realized that sin should be cos.