0.28 Phy1250: circular motion -- acceleration and centripetal force

Table of contents

• Preface
  • General
  • Prerequisites
  • Supplemental material
• Discussion
  • Subtraction of vectors
  • An old-fashioned merry-go-round
  • A weight on a string
  • Water in a bucket
  • The moon and the Earth
  • The work-energy explanation
  • Centripetal, not centrifugal
  • Summary
• Example scenarios
  • Scenario #1
  • Scenario #2
  • Scenario #3
• Resources
• Miscellaneous

Preface

General

This module is part of a book (or collection) designed to make physics concepts accessible to blind students. The collection is intended to supplement but not to replace thetextbook in an introductory course in high school or college physics.

This module explains acceleration and centripetal force in a format that is accessible to blind students.

Prerequisites

In addition to an Internet connection and a browser, you will need the following tools (as a minimum) to work through the exercises in these modules:

• A graph board for plotting graphs and vector diagrams ( (External Link) ).
• A protractor for measuring angles ( (External Link) ).
• An audio screen reader that is compatible with your operating system, such as the NonVisual Desktop Access program (NVDA), which is freelyavailable at (External Link) .
• A refreshable Braille display capable of providing a line by line tactile output of information displayed on the computer monitor ( (External Link) ).
• A device to create Braille labels. Will be used to label graphs constructed on the graph board.

The minimum prerequisites for understanding the material in these modules include:

• A good understanding of algebra.
• An understanding of the use of a graph board for plotting graphs and vector diagrams ( (External Link) ).
• An understanding of the use of a protractor for measuring angles ( (External Link) ).
• A basic understanding of the use of sine, cosine, and tangent from trigonometry ( (External Link) ).
• An introductory understanding of JavaScript programming ( (External Link) and (External Link) ).
• An understanding of all of the material covered in the earlier modules in this collection.

Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programming tutorials. You will find a consolidated index at www.DickBaldwin.com .

Discussion

I purposely published an earlier module titled Vector Subtraction for Blind Students in preparation for this module.

An unbalanced net force is required

As you learned in an earlier module, in order for an object to travel in a circle under uniform circular motion, a force must act on that object to causeit to stay on the circular path. Otherwise, according to Newton, the object will fly off into space at a constant velocity (ignoring both air resistance andgravity).

Change of direction equals acceleration

Whenever the velocity vector that describes the motion of an object changes direction, that object has undergone an acceleration, even if the magnitude ofthe velocity vector hasn't changed.

Continual change in direction