Mr. Rogers' Honors Physics

Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter
Momentum (9)
Energy (10)
Energy (11)
Heat (12)
Matter (13)

Momentum-- Chapter 9

Relevance: Conservation of momentum is a key concept used for analyzing collisions including highway crashes.

SC Standards :


P-3.5 Explain the factors involved in producing a change in momentum (including impulse and the law of
conservation of momentum in both linear and rotary systems).
P-3.6 Compare elastic and inelastic collisions in terms of conservation laws.


Practice Test Study Guide


Essential Question: Why is it hard to stop a train?

Conservation of Momentum

  1. Define momentum 2 ways.
    1. How hard it is to stop an object
    2. P ≡ mv
  1. State that momentum is a vector.

  2. Explain what conservation of momentum means. The sum of the momentums of the particles immediately before an event (see objective 4) is equal to the sum of the momentums of the particles immediately after the event.

  3. Name two types of situations where momentum is conserved.
    1. Explosions - things flying apart
    2. Collisions - things flying together
  1. State one of the key reasons momentum can be conserved. - It's a vector!

  2. Solve 1 dimensional "explosion" problems using conservation of momentum.
    • Bubba shoots a rifle
    • Bubba shoots a rail gun
    • Bubba pushes Nancy
  1. Solve 1 dimensional collision problems using conservation of momentum when the colliding objects stick together.
    • Bubba is hit by a projectile
    • Meteors collide and stick together

Homefun (formative/summative assessment): Read sections 9.1


Formative Assessment: Physics Investigation

Research Question  
Data, Calculations  

Follow up Questions




Essential Question: How much force can you withstand?


  1. Define impulse mathematically 2 different ways, in a special case, and explain in general terms what it indicates.
  • (imp) ≡ ΔP
  • The area under the force vs. time curve
  • (imp) = Ft , note this is a special case when F = a constant
  • Roughly speaking: an indication of how much effect a force will have on changing an object's momentum
  1. State that impulse follows Newton's 3rd law.

  2. Solve impulse problems.

    car crashes

area under the F vs t curve


Homefun (formative/summative assessment) problems1, 2, 3 p. 233.


Essential Question: What makes a spinning ice skater spin faster when she pulls her arms in?

Angular Momentum

  1. State the mathematical definition of angular momentum. L = I w
  2. State that angular momentum can only be changed by creating a torque (twisting action) on an object for a period of time. This torque for a period of time is an angular impulse. t (Δt) = ΔL
  3. Explain why an object in orbit has constant angular momentum. The gravity force acts through the object's center of mass, hence cannot create a torque on it.
  4. Given a satellite in elliptical orbit, derive the highest velocity given the lowest velocity and the distance from the planet at each point. Relevance: Constant angular momentum explains why comets speed up as they approach the Sun.
  5. Solve spinning ice skater problems. Spinning ice skaters can be modeled as having constant angular momentum.

Homefun (formative/summative assessment):Section Review Problems 7, 8 ,9, 11, 12; page 235

Essential Question: How is billiards a physics problem?

2D Collisions

  1. Describe the difference between elastic and inelastic collisions.

Note: kinetic energy is the energy of motion

K = 1/2 mv^2

where: m = mass, v = velocity

Collision Type Conservation  Momentum Converts Some Kinetic Energy to Heat. Particles Stick
Elastic Yes No No
Inelastic Yes Yes Yes


  1. State that the only truely elastic collision occurs between molecules.

  2. Describe 2D elastic collisions When a moving mass collides with a stationary mass of the same size in a glancing elastic collision, the momentum vectors form a 90 degree angle after the collision.

    • the y-components of the two momentum vectors cancel
    • the sum of the x-components of the 2 momentum vectors afterwards= the momemtum before


  3. Calculate the final velocity for 2D inelastic collisions.


Homefun (formative/summative assessment): problems 22, 23, page 243


Essential Question: How can you best prepare for the test?

Review of Objectives 1- 19 (1-3 days)

Formative Assessments:

  1. Work review problems at the board.

  2. Work practice problems.

Metacognition Problem Solving Question: Can I still work the problems done in class, several hours or days later? Some amount of repetition on the exact same problems is necessary to lock in learning. It is often better to thoroughly understand a single example of a problem type than to work example after example understanding none of them completely.

Relevance: Good test preparation is essential to performance in physics class.

Homefun (formative/summative assessment): problems 81, 89, 91, 59 pages 193-194; problems turn in on the day stapled to the back of the test.

Summative Assessment: Unit exam objectives 1-23


SAM Team--Southside High School's STEM and Computer Science extra-curricular club (Mr. Rogers Sponsor)

Mr. Rogers' Twitter Site

Mr. Rogers Teacher's Blog

Mr. Rogers T-shirts

Mr. Rogers Information for Teachers

Mr. Rogers Science Fair Information

Check out other web sites created by Mr. R:

Check out Articles by Mr. Rogers:

Insultingly Stupid Movie Physics is one of the most humorous, entertaining, and readable physics books available, yet is filled with all kinds of useful content and clear explanations for high school, 1st semester college physics students, and film buffs.

It explains all 3 of Newton's laws, the 1st and 2nd laws of thermodynamics, momentum, energy, gravity, circular motion and a host of other topics all through the lens of Hollywood movies using Star Trek and numerous other films.

If you want to learn how to think physics and have a lot of fun in the process, this is the book for you!


First the web site,

now the book!

Mr. Rogers Home | Common Sylabus | AP Comp Sci I | AP Comp Sci II | AP Physics Mech | AP Physics E&M | AP Statistics | Honors Physics|IB Design Tech | Southside

[ Intuitor Home | Physics | Movie Physics | Chess | Forchess | Hex | Intuitor Store |

Copyright 1996-2011 T. K. Rogers, all rights reserved. Forchess is a registered trademark of T. K. Rogers.
No part of this website may be reproduced in any form, electronic or otherwise, without express written approval.