## Elastic and Inelastic Collisions, Notes from Tutoring Physics

We went over a collision that was in two different parts assumed to be elastic and inelastic.

For an elastic collision, energy is conserved and momentum is conserved.

For an inelastic collision, only momentum is conserved.

So momentum is conserved in either situation.

You can derive equations by using those two ideas for an elastic collision (which takes a few steps). Or you can also use equations that are similar to the purpose of the ‘range equation’ seen previously  in this class.

The work for the inelastic collision ends up being simpler.

## Tutoring Physics 2A at MPC Before Test 1

We looked at how two of the kinematic equations are most fundamental to the problems for the first three chapters. Also looked at how the summation of the forces will be zero if there is no acceleration.
For one problem, it could be solved with the quadratic formula or in a different order without it.
Drawing a diagram and then writing the general equations would be one way to start many of the problems.

The first test covers the first five chapters.

## How to figure out gravity on Mars

Leave comments with any questions you have.

## Problems to Focus in Preparation for the Final

Here is a guide to some problems to focus on for the final.  If you understand how to work all of these problems, you should be prepared for the final.  The concepts may be combined in different ways though.

Homework Problems:

Chapter 10: 32

Chapter 14: 6, 11, 24, 35, 52

Chapter 15: 2, 30, 37, 42, 52, 70

For chapters 1-13, focus on the relevant questions on the tests/quizzes.

Weather balloon problem

Snowboarding Problem (with angles)

Cannon Problem

Racetrack problem

Planetary Gravitation problem

Penguin/Rhino torque balance

Penguin sliding quiz

Buoyancy quiz

http://nealien.com/test-1-solutions.htm

http://nealien.com/test-2-solutions.htm

http://nealien.com/test-3-solutions.htm

http://nealien.com/test-4-solutions.htm

## HW #14 Solutions – (Chapter 15)

Here they are, a few are a bit dark, but you should be able to read them (you can click on the images and enlarge them), let me know if you have questions.

## Final Outline

The final will be Thursday December 15th at 8 AM.

Bring a note card, include equations from chapters 14 and 15 and what else you would like.  Equations from previous chapters as well as constants will be provided.

Problems will include these topics (not necessarily all of them)

1.  Wave on a string
2.  Pendulum
3. Intensity/Wave Propagation
4.  Sound, Damping
5. Sound Wave – amplitude/velocity/acceleration
6. Sound & dB problem
7.  Doppler Effect
8. Ideal Gas
9. Rocket/kinematics
10. Friction, circular motion
11. Torque, center of gravity, buoyancy, gravity
13. spring energy, potential energy, kinetic energy
14. Bernoulli (likely extra credit)

## Test 4 Solutions

Here are the solutions to the fourth test.  Let me know if you have questions.

## Test 4 Outline

Here are some problems you should review:

Chapter 10 Problems:8, 14, 25, 27, 36, 43, 51, 56, 63

Chapter 11 Problems:9/11/12, 21, 23/27/29/54, 40, 43, 46

Chapter 12 Problems:6/12, 27, 33/38, 45, 55/59

Chapter 13 Problems:6, 8, 13, 17, 22, 39, 43, 48

The test will have about 12 problems, something along these lines:

1.  Kinetic energy equivalency

2.  Kinetic energy/potential energy motion

3. Chemical energy -> physical process

4.  Heat Engine Problem

5. Buoyancy Problem

6. Fluid/Pressure Problem

7.  Ideal Gas- temperature, expansion Problem

8. Gravitational/elastic/kinetic energy problem

9. Something like weather balloon problem

10. Specific heat and heat of transformation

11. Heat transfer

12. Pressure/fluid dynamics (Bernoulli)

## Test #3 Solutions

Here are the solutions.

## Test #3 and HW Problems to Focus on

Here is how I looked at the homework problems.  They are grouped in similar themes.  The ones in the bold will likely show up, or a problem similar to them.

Chapter 7 Problems:
1/2 – discus, hard disk
9 14 – torque/force
21 – torque
24 – center of gravity
27/32/35/39 – kinematic, torque,
moment of intertia
42 – rolling motion

Chapter 8 Problems:
6/8/9/15 – torque balance
spring – 19/22/23
Young’s Modulus 27/28/32
41 – angle, rope, pull

Chapter 9 Problems:
1 equal momentum
13 conservation of mom.
15/22 – bullet through block, baseball
inelastic 25
26, 2D collision
planet angular momentum 30
33 angular momentum
spinning? 35
throw ball on ice lake
55 huge collision
rocket! 61
Cannon- 63