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Inelastic collisions (where they stick together)

Page 10: Inelastic Collisions (where they stick together)

Problems

1. A 2000 kg train car is not moving.  What is its momentum?

2. A 2000 kg train is moving at 10 m/s.  What is its momentum?

3. A 2000 kg train car moving 1 m/s couples with another 2000 kg train car that is stationary.  How fast are the coupled cars moving after the collision?

4. A 20 ton train car moving at 3 m/s couples with a 10 ton train car that is stationary.  How fast do the coupled train cars move away?

5. A 50 kg running back moving at 4 m/s, runs into a 100 kg lineman who is standing still.  If the lineman grabs him, how fast will the two move away from the collision?

6. A 0.1 kg bullet traveling at 100 m/s hits a 2 kg wood block that is not moving.  If the bullet embeds itself into the block, how fast does the block and bullet move?

7. A 0.1 kg bullet traveling at 100 m/s hits a 100 kg man standing still.  If the bullet embeds into the man’s chest, how fast will the man be thrown backwards?

8. A 0.1 kg bullet traveling at 100 m/s hits a 50 kg man standing still.  If the bullet embeds into the man’s chest, how fast will the man be thrown backwards?

9. A 500 kg car runs into another 500 kg car that is at a stop sign.  If they both stick together and move at 4 m/s, how fast was the moving car going?

10. A 500 kg car moving at 20 m/s hits a 2000 kg truck at a stop sign.  If the car and truck move off together, how fast will they be traveling?

Pass out Physics Knowledge Grid.  [This is going to be page 7 in your notes.]

Momentum Questions for PH2 d and PH2. gB.  [This will be page 8]

[PH2. d.]

1. A gun fires a bullet of mass 0.1 kg at 100m/s. What is the momentum of the bullet?

2. A 1000 kg car going down the road at 20 m/s has what momentum?

3. If an astronaut throws a 3.0 kg air tank with a velocity of 5.0 m/s, what is the momentum of the air tank?

4. A 0.3 kg ball moving at 4 m/s has what momentum?

Check your answers with those around you and put a plus sign in the “Self” column if you were able to get them all right. In the notes section, put the equation you used and the page in your notes where you can find help to do the problems.

[PH2.gB]

5. If the bullet in #1 hits a bowling ball and the bullet comes to a stop after the collision, What will be the momentum of the bowling ball after the collision?

6. If the bowling ball in #5 has a mass of 5 kg, what will its velocity be after the collision?

7. . A 50 kg running back runs at 4 m/s toward the end zone.  What speed would a 100 kg lineman have to hit him in order to stop all his motion?

8. A 0.3 kg ball moving at 4 m/s runs into another ball with a mass of 0.3 kg, giving it all its momentum, what will the second ball’s speed be?

Check your answers with those around you and put a plus sign in the “Self” column if you were able to get them all right. In the notes section, put the equation you used and the page in your notes where you can find help to do the problems.

Research Project:  If all the people on the earth jumped off a 10 meter high building and hit the ground at the same time, what velocity would they give to the Earth?  Do each step in your notes on page 9.  Complete for homework if you don’t get it done in class.

To do this:

1. Find out how many people there are on the earth ____________________ (round off all numbers to one or two digits to make your calculations easier)

2. Estimate the mass of the average person (in kg) ________________________

3. Multiply the two together to find the total mass of all the people on the earth. _______________

4. Figure out how fast something is going after it falls from a 10 m height. [hint: find the drop time and then use s = at]  ___________________

5. Calculate the momentum of all the people after they jump off a 10m building [p=mv] ____________________

6. Find the mass of the Earth _________________________

7. Find the velocity of the Earth if it is given the momentum in #5 [v=p/m] __________________

Page 5

Conservation of Momentum Notes

Page 6

Run the following simulation: Air Track Simulation.

1. Draw the track and the carts.

2. Run the simulation with the red cart with mass = 1, initial velocity =100, and the blue cart mass =1 and initial velocity = 0.  Describe what happens after they hit.

Calculate the momentum of each cart before the collision and after the collision.

Find the total momentum before the collision and after the collision.  How do they compare?

3. Increase the mass of  the red cart to 2.

Describe what happens after they hit.

Calculate the total momentum before the collision and after the collision.  How do they compare?

4. Increase the red cart’s mass to 3 and describe what happens.  Find the total momentum before the collision and after the collision  How do they compare?

Allow the simulation in #4 to run for a while and notice if the total momentum ever changes?  Does the red cart ever get all its momentum back?  What is the blue cart doing when the red cart has its original momentum back?

5. Where it says “Scenarios,” make it say “m1 = m2 inelastic”  Run the simulation and describe what happens.  Find the total momentum before the collision and then after the collision.  How do they compare? Remember that they are stuck together, so the total mass is m1 + m2.

6. Make the red cart start with a velocity of 100 and the blue with a velocity of -100 for an inelastic collision.  Describe what happens.  What is the total momentum before and after the collision.

7. Play the Sumo Wrestling Game and see who can win.

1. Video

2. Momentum notes (Page 3)

2. Momentum problems (page 4)

Find the momentum of the following:

1. a 1000 kg automobile with a velocity of 10 m/s.

2. a toy dart gun of mass .035 kg and a velocity of 4 m/s.

3. a Boeing 737 at take off velocity (65 m/s) with a mass of 145,000 kg.

4. a 0.45 Caliber bullet (m = 0.162 kg) leaving the muzzle of a gun at 860 m/s.

5. a 110-kg professional fullback running across the line at 9.2 m/s.

6. a 360,000-kg passenger plane taxiing down a runway at 1.5 m/s.

Calculate the velocity of the following:

7. a 2 kg bowling ball that has the same momentum as the automobile in #1.

8. A 0.001 kg fly that has the same momentum as the automobile in #1.

9. A 50 kg running back that has the same momentum as the automobile in #1.

10. A 100 kg lineman that has the same momentum as the Boeing 737.

Quiz 6 retake

Page 2 in notes.

Announcements:

Test on Friday covering everything from the beginning.  Quiz 6 covers most of it.

Quiz 6 retake tomorrow for everyone.

A couple cool things: Photopic Sky Survey, Minute Physics Time’s Arrow.

Return Quiz 6

For every question you missed, do the following. If you missed less than 7, do this for any 7 of the questions.

1. Find out where in the notes there is a similar question or notes explaining the question. Write down the page number.
2. Write out the steps you need to take to find the answer.
3. Write a new question with different numbers and different objects. Calculate the new answer showing your work as well as the answer.

Homework: Study all the questions on the quiz and be prepared to take Quiz 6 again tomorrow without notes.

Page 1 in your notes

Circular motion examples: Bowling ball and skater,

Today you will study circular motion. For this simulation use Firefox.

1. Answer the questions on the activity sheet here. Write all questions or print the activity sheet out.

Note: for #8, directly means if you increase one, the other increases. Inversely means if you increase one, the other decreases.

2. Open the simulation here.

Practice for Quiz 6.  We will take the quiz tomorrow.

Answer each question in your notes.

1. If you push a chair with a force, it accelerates. If you double the force on the chair, what happens to the acceleration of the chair?

2.  If you push a chair with a force, it accelerates.  If you double the mass of the chair, what happens to the acceleration?

3. If you kick a 0.35 kg football with 20 N of force, what force does the football exert on your foot?

4. Draw the free body diagram of a box sitting on a table.

5. Draw the free body diagram of a football After it was kicked.

6. Newton’s First Law explains how a moving ice skater, in the absence of friction, will do what?

7. If a small truck and a large truck have the same size engine. What will the acceleration of the small truck be compared to the large truck?

8. A bus cannot stop as fast as a car. The reason is because the bus has a greater what?

9. A bag of rocks weighs 90 N. What is the mass of the bag of rocks?

10. A 1,000 kg rocket accelerates at 20 m/s². What is the force exerted by the rocket engine?

11. It takes 100 Newtons of force to accelerate a skate board at 5 m/s². What is the skateboard’s mass?

12. You push a 5 kg crate with a force of 50 N. What will the crate’s acceleration be?

13. A car traveling at a constant speed of 35 m/s for 20 seconds has what acceleration?

14. What is the weight of a dog whose mass is 3.4 kg?

15. A boy pushes on a 10 kg crate with a force of 5 N to the right. Another boy pushes with a force of 15 N to the left. What is the acceleration of the object?

16. If you travel 100 miles North and then 100 miles South, what total distance have you traveled? What is your displacement?

17. If you travel 100 miles North in 2 hours and then 100 miles South in 3 hours, what is your velocity?

18. An apple falls from a tree and takes 1.2 seconds to fall. How high was the apple?

19. You kick a rock with a force of 100 N. The rock exerts a force back on your foot of how much and in what direction? Which of Newton’s laws explains this?

20. You throw a soda bottle up in the air. When the bottle is half way to the top, what is the acceleration of the ball? What is the weight of the ball? What formula do you use to calculate weight?

21. The earth is pulling on you with a force equal to your weight. You are pulling on the earth with an equal force. What law explains why? How come you can’t move the earth?

Free body diagram notes

Go through the tutorial linked here.

1. Write down the steps to draw a free body diagram.

2. Draw each example free body diagram that is shown, label the force vectors,  and describe what is happening in words.

3. Draw each diagram that you have to construct.  Don’t draw the picture of what is happening, draw the free body diagram and describe in words what it is a diagram of.