1. A 45 kg sled is pulled at a constant velocity across a horizontal slippery surface. If a force of 320.0 N is being applied to the sled rope at an angle of 28.0 degrees to the ground, what is the coefficient of kinetic friction of the surface?

2. A 15.0 kg box is sliding down a 25.0 degree slope with a constant velocity. What is the coefficient of kinetic friction?

3. A 40.0 kg crate is carried in a pickup truck that accelerates at 0.55 m/s2. What is the coefficient of static friction between the crate and the truck bed if the crate does not slide?

4. What is the net force acting horizontally on a 154kg cart if the cart is accelerated across a level road at 0.25 m/s2?