Assignment

1. A 20 N crate is held at rest on an incline by a rope that is parallel to the incline as shown on the figure to the right. The incline is 30 degree above the horizontal. The coefficient of static friction, μs, between the crate and the incline is 0.35.

a) Draw two free body diagrams for the forces acting on the crate. In the first, indicate the forces pointing along the track and in the second, indicate the forces pointing perpendicular to the track

b) Rank all forces acting on the crate from largest to smallest.

c) Write down two separate equations for Newton’s second law with static friction: one for forces pointing along the track and one for forces pointing perpendicular to the track. Do some forces appear in only one of the Newton’s law equations? For forces that have some component in both, make sure you break down those force vectors correctly in the equation.