Physics 213 Quiz 6 Forces IV & Mom 5 pts each Nov. 5, 2005

1.

Make a two column table showing all the forces acting on the bottom block of mass m and all the reaction forces to those forces.

Action

Reaction

2. A 0.2 kg plastic cart and a 2 kg lead cart can both roll without friction. Equal size forces used to push each cart for 1 second, starting from rest. After the force is removed at t = 1 s, which of the following statements are true?

The momentum of the plastic cart is less than the momentum of the lead cart.

The momentum of the plastic cart is equal to the momentum of the lead cart.

The momentum of the plastic cart is greater than the momentum of the lead cart.

There is not enough information to compare the momenta of the two carts.

a. Circle the correct statement.

b. Explain your choice.

3. A 60 kg kid on a 200 kg bumper car is moving to the east at 80 m/s. He has a head-on perfectly inelastic collision with another identical car that is moving west at 30 m/s and containing two large adults of equal mass. The cars collide and stick together and travel east at a speed of 5 m/s, how much do each of the adults weigh in newtons?

4. A 100 kg slab is supported by three ropes and two 50 kg pulleys. The system is stationary.

Find T.

Wanna prove your stuff? Do the problem on the next page instead of problems 5 & 6. Not only will you get credit for problems 5 & 6, you'll also get 5 points bonus! Warning, the next page is only for the brave.

5. A 200 g canary is flying east at a constant 1 m/s when she experiences a sudden force due to a gust of wind. The impulse delivered to the terrified bird is indicated in the following F vs t graph. What are the canary's speed and direction after the gust ends?

6. a. A 2kg ball of clay is hurled horizontally at a door at a speed of 30 m/s. It hits the door and sticks to it. What impulse is delivered to the door?

b. A 2kg rubber ball is hurled horizontally at a door at a speed of 30 m/s. It hits the door and bounces straight back at the same speed with which it was thrown. What impulse is delivered to the door?

c. If you really wanted to close that door, which is the best item to throw at the door, the clay ball or the rubber ball?

A 500 g cart rolls down a 30° incline from rest a distance of 1 m. It bounces off a rubber bumper at the bottom of the hill and produces the F vs t curve shown below. After impact, how far does the cart roll back up the ramp ?

Note: In the figure below, ms means milli seconds.