Physics Assignment 3

Read over the Momentum Basics page linked on the homepage of physicsclub.

Work through the following physlets (linked at http://www.physicsclub.net/physletIndex/momentumImpulse.html and within the question). Just follow the directions on each and keep notes on paper. The answers will be with the answer to the web question, but you need not include it in your web response.

1. Ball and Flower Pot

2. Hammer and Nail

3. Explosion CM (CM stands for center of mass)

4. Cars and Walls

Reading:

1. Section §4.5 of your text. Be sure you can define mass and weight. Name the m-k-s units for each. Be able to convert from one to the other on earth and on the moon.

2. §5.3 of Hewitt and §6.2 of Hewitt. Be able to compare the force that a baseball exerts on a pitcher to the force that the pitcher exerts on the baseball.

3. Chapter 7 in your text.

4. "The Physics Classroom" http://www.physicsclassroom.com/Class/momentum/ : a nice alternative to a traditional text with animations etc.

Answer the following text questions in your notebook (not on the website, but before working on the website).

Review questions: 2, 4, 5, 6, 8, 10, 11 page 100

Simple Problems about Rosebud over a Period of Coasting on a Horizontal Field of Snow (or Were There References to Classical Mechanics in Classic Movies of the Day?)

1. How much momentum is possessed by a 5 kg sled moving horizontally at 8 m/s?

2. How much acceleration is experienced by this sled if it slows down to 3 m/s over the next 10 seconds?

3. By how much does the sled's momentum change in that time?

4. The "rate of anything" is usually just "anything" ÷ by how much time it took. At what rate did the sled's momentum change? **Important note: the rate of change of momentum is usually called "Net Force".

5. So what is the net force on the sled during the 10 seconds here?

6. Essay: Describe what happened to the sled in a sentence or two, using the words "momentum", "net force", "velocity" and "impulse".

Simple 1-D Inelastic Collisions

1. A bug and a bus, each moving 20 m/s but in opposite direction collide head on.

1a. compare the force experienced by the bug to the force experienced by the bus.

1b. compare the change in momentum experienced by the bug to the change in momentum experienced by the bus.

1c. compare the acceleration experienced by the bug to the acceleration experienced by the bus.

2. A 5000 kg rail car moves west at 12 m/s and collides with (and "couples" with) a 6000 kg rail car moving east at 8 m/s. Assuming that momentum is conserved, at what rate does the resulting two car train move?

2a (is kinetic energy conserved? yes or no and how do you know?)