Mr. Rogers' AP Physics C: Mechanics (With IB Physics Topics) Objectives

Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter
Gravity   Circular Motion Statics Rotation  

Chapter 6: Circular Motion 

AP Physics C Newtonian Mechanics:

E. Circular motion and rotation 6% (estimated), cumulative 88%
    1. Uniform circular motion 

Practice Test Study Guide

Objectives

Essential Question: What is the difference between centripetal and centrifugal force and is centrifugal force real ?

Section 6.1, 6.2

  1. Explain why centripetal force never shows up on a free body diagram.

  2. Solve conical pendulum problems (horizontal circle).

  3. Solve road bank problem given static friction = 0 (horizontal circle, see drawing at right).

  4. Derive an expression for the critical speed of a roller coaster loop (vertical circle).

  5. Derive an expression for the ramp height needed to achieve the critical velocity in a roller coaster loop (vertical circle).

  6. Derive an expression for the tension in the rope used for swinging a mass at constant velocity in a vertical loop (vertical circle).

Homefun: Problems 13, 15, 21, 57, 55.

Homefun: Questions 1 - 11 p.44-45; prob 1, 3, 5, 7, 9

Read: Insultingly Stupid Movie Physics
Chapter 15, Scenes with Artificial Gravity: The Good, Bad, and Ugly Space Stations, pp 99 - 115

 

Metacognition Problem Solving Question 6.1: When solving a circular motion problem always ask which forces have components in the radial direction. The sum of these components is the centripetal force.

Metacognition Problem Solving Question 6.2: If circular motion is present, What dimension is the the circle in? All circles in the AP test will be either vertical or horizontal except for space stations in which case it doesn't matter. This is important since it indicates the plane which contains the radial direction (see Metacognition Principle 6.1)

 

Activities

Lesson 1

Key Concept: Centripetal force is the sum of the forces directed toward the center of rotation.

Purpose: Gain a deeper understanding of the circular motion equations.

Interactive Discussion: Objective 1. Why does centripetal force never appear on a FBD? 

Demo 1: Demonstrate the critical velocity in a vertical loop using a commercial loop track.

In Class Problem Solving: Objectives.

  1. The conical swing.
  2. Batman drives the Batmobile on a slippery slope.
  3. The world's most exciting rollercoaster.
  4. Loop the loop ramp height calculation.
  5. Tarzan's amusement ride.

Resources/Materials: The loop the loop demonstration.

Essential Question: Is a fictitious force something out of a novel?

Section 6.3

  1. Explain how fictitious forces appear both in systems which are accelerating in linear and uniform circular motion.

  2. Find the angle a rope makes when it is suspended from the roof of an acceleration rail car.

Metacognition Problem Solving Principle 6.3: The sum of the components in the dimension  of acceleration provide the force causing linear acceleration.

 

Homefun: prob. 23, 25 Serway

Lesson 2

Key Concept: Fictitious forces

Interactive Discussion: Objective. Which of Newton's laws established where the frame of reference must be located?

In Class Problem Solving:

  1. Rail car problem

Mini-Lab Physics Investigation (Requires only Purpose, data, and conclusion)

Title Analysis of a Circular Motion on a Vertical Track
Purpose Determine the height on the track's entrance ramp from which a roller must be released for it to make a complete circle without falling off the track.
Overview
  1. Measure height from the top of the circle.
  2. Run multiple trials for both the steel roller and the mouse roller (rubber surfaced)
Data, Calculations Calculate an expected value for the height using energy equations and calculate a % difference between the expected value and the average value measured for each of the 2 rollers.
Questions, Conclusions
  1. Why is the required height much greater than expected? Is it a problem with the mathematical model or just some form of random error or experimenter ineptitude? (Hint: If more energy was used than expected, it had to go somewhere. Click the button at the top labeled rotation and look for a possibility.)
  2. Do both rollers have to start from the same height? If not, then why would one roller need to be started from a greater height than the other?

 

Resources/Materials: circular track, steel roller, mouse roller, meter stick
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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!


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