Need help with showing work for these questions:

1. A 50.0 kg steel file cabinet is in the back of a dump truck. The truck's bed, also made of steel, is slowly tilted. What is the magnitude of the static friction force on the cabinet when the bed is tilted 20 ? At what angle will the file cabinet begin to slide?

2. In the sport of parasailing, a person is attached to a rope being pulled by a boat while hanging from a parachute-like sail. A rider is towed at a constant speed by a rope that is at an angle of 15 from horizontal. The tension in the rope is 2300 N. The force of the sail on the rider is 30 from horizontal. What is the weight of the rider?

3. A horizontal rope is tied to a 50 kg box on frictionless ice. What is the tension in the rope if

a. The box is at rest?

b. The box moves at a steady 5.0 mis?

c. The box has Vx = 5.0 mis and ax = 5.0 m/s2 ?