Physics 213 Quiz # 5 12 points each Friday 10-27-2006

Note: In all the problems on this test, use g = 10 m/s² .

1. Two blocks connected by a massless rope are being dragged by a force of 60 N, as indicated in the figure below.

If m₁ = 4 kg and m₂ = 8 kg, and µ_k = 0.3 , find

a. Find the acceleration of the system.

b. Find the tension T in the rope.

2. Elvira pushes on the box with all her might horizontally. The block acclerates up the hill 2 m/s². If the coefficient of kinetic friction between the box and the hill is µ_k = .4, what is the force F with which Elvira pushes the box?

3. A 1000 kg car goes over a hill and is located as indicated on the figure below.

a. Find the normal force of the hill on the car at this point if it is at rest. b. Find the normal force if the car is moving at 40 mph.

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4. A 5 kg penguin sits on a 12 kg sled as shown in the figure below. A horizontal force of 45 N is applied to the sled, but the penguin attempts to impede the motion of the sled by holding onto a rope attached to the wall. The coefficient of kinetic friction betwen the sled and the snow, as well as between the penguin's feet and the sled is 0.2.

a. Draw a FBD for the penguin. b. List all the forces acting on the penguin c. List the reaction force for each force acting on the penguin.

5 Points Bonus!! Find the tension in the rope

5 More Points Bonus!!! Find the acceleration of the sled.