Test
Show all work. All angles given are from horizontal.
1. A 10 kg wagon is pulled horizontally with a horizontal force of 20 N. There is a friction force of 5 N. Starting at rest, it is pulled for 6 s, then the 20 N is removed but the 5 N remains. Find the total distance traveled from the start to the point where it stops. Sketch a graph of v vs t well beyond 6 s.
2. A football is kicked off the ground with Vo = 6 m/s @ 30 degrees. Find a) the time to reach the highest point. b)distance x from the kickoff point to the point where it hits the ground.
3. A box of mass 5 kg is pulled with force 20 N at a 30 degree angle above horizontal. The coefficient of kinetic friction between box and floor is 0.2. Find the acceleration.
4. Mass 3.0 is tied to a string and swung around in a vertical circle of radius 0.60 m in such a way that its speed is a constant 6.0 m/s. Find two tensions: when it is at the bottom and at the top.
5. A block of wood is on a plank 3 meters long inclined at an angle of 30 degrees. The coefficient of kinetic friction is 0.2. If it starts with v = 0 at the top, find a) the time it takes to reach the bottom and b) the heat generated while it is on the incline.
6. A 20 kg child is coasting at 3 m/s in a 10 kg wagon. He jumps off the front in the forward direction with v = 2 m/s relative to the wagon's final v. Find the final velocities of both, relative to the ground.
7. Write the conservation of energy equation for this situation: a roller coaster has speed vo at the top of a hill of height y. On the way down, the absolute value of the work done by drag forces is Wf. The speed at the bottom is v.
8. A 3.0 meter long uniform rod, mass 0.40 kg, is hinged at the lower end. It is tilted at an angle of 60 degrees and released. a) Find the initial angular acceleration. The inertia of a rod about its end is (1/3)ml2. Remember that to calculate torque, it is as if all weight is concentrated at the center of gravity. b) Find the angular speed when the rod is horizontal, using an energy approach.
My main pages:
mechanics
fluids, heat, electricity and magnetism
vibrations and waves
quantum
alphabetical quickies at index.