#1. A 50.0 kg crate slides across a horizontal surface at constant speed when a horizontal force of 160 N is applied to it. What is the coefficient of kinetic friction between the crate and surface?

#2. Two blocks are connected by a light string passing over a pulley. The inclined surfaces are fricitonless and the effects of the pulley can be ignored. If the values are mass m₁=2.00 kg m₂=1.00 kg, theta₁=36^o, and theta₂ = 56^o, what is the acceleration of the blocks?

#3. A highway curve with radius 275 m is to be banked so that a car traveling 25 m/s will not skid sideways even in the absence of friction.
a) Draw a free body diagram of the car and sum forces.
b) At what angle should the curve be banked?

#4. Chuck is playing on a tire attached hanging from a tree by a rope. The rope on the tire is 2.10 m long. A friend pulls him back until the rope is 42^o from the vertical and releases him from rest.
a) How fast will he be moving at the bottom of the swing?
b) How fast is Chuck moving when he swings up to an angle of 32^o on the other side of the vertical?

#5. How much work is done by a force F = (2xi + 3j)N, that moves a particle from a position r_i = (2i + 3j)m to a position r_f = (-4i - 3j)m?

#6. Shawn (m = 45.0 kg) rides his skateboard at a local skate park. He starts from rest at the top of the track as seen below. He begins his descent down the track, always maintaining contact with the surface. The mass of the skateboard is negligible, as is friction except where noted. As Shawn goes down the last slope he is able to produce a friction force with a magnitude of 120.0 N. What is his speed when he reaches the bottom of the last incline (at the end of the 18.0 m slope)?

Answers:

1. .33
2. 1.13 m/s² to the left
3. 13^o
4. 3.3 m/s, 2.1 m/s
5. -6 J
6. 11.8 m/s