# B.1. Rigid Bodies and Rotational Dynamics

In Section 6.1 we looked at motion in a circle, but exclusively at objects moving at constant speed round a circle. We understood the idea that even though their speed is constant, they are accelerating because there is a resultant centripetal force acting. Now, we will build upon these ideas to look at objects that are not travelling at a constant speed - i.e. they have an angular acceleration. Most of the stuff we look at has analogues with some of the linear motion stuff we looked at tin the beginning. For example, we have angular suvat equations, we have angular momentum, we have rotational equilibrium and angular equivalents of Newton's laws.

#### Torque

To start off with, we need to make sure we are confident with the various concepts of displacement, velocity and acceleration (and their scalar equivalents). If you need a bit of a recap, flick back to the section on vectors (particularly resolving, addition and subtraction).

## Video Lessons

Chris Doner | Torque | IB Specific | ||||

Khan Academy | Introdution to Torque | Torque of Angled Forces | ||||

Physics Online | Principle of Moments | Couples | ||||

Science Shorts | Rotational Dynamics Overview |

## Resources

IB Physics | Option B Notes (Core) | |||||

Isaac Physics | Balancing Moments/ Torques | Torques | Level 3/4 applicable to this section | |||

Mr. G | B.1 Teaching Notes | B.1 Student Notes | ||||

Physics and Maths Tutor | Engineering Definitions | Engineering Key Points | Engineering Detailed Notes | Rotational Dynamics Flashcards | A Level Resources - content slightly different |

## Questions

Dr French's Eclecticon | Statics and Moments | Link to Dr French's Site | Extension: Pre-University Material | |||

Isaac Physics | Moments | |||||

Physics and Maths Tutor | Torque and Angular acceleration (AQA 1) | Torque and Angular acceleration MS (AQA 1) | A-Level Qs: overlapping content |

#### Moments of Inertia

## Video Lessons

Chris Doner | Rolling Inertia | IB Specific | ||||

Khan Academy | More on Moments of Inertia | |||||

Science Shorts | Rotational Dynamics Overview |

## Resources

IB Physics | Option B Notes (Core) | |||||

Isaac Physics | Moments of Inertia | Level 5/6 beyond IB | ||||

Mr. G | B.1 Teaching Notes | B.1 Student Notes | ||||

Physics and Maths Tutor | Engineering Definitions | Engineering Key Points | Engineering Detailed Notes | Rotational Dynamics Flashcards | A Level Resources - content slightly different |

## Questions

Dr French's Eclecticon | Moments of Inertia and Rotational Dynamics | Solutions 1 | Solutions 2 | Link to Dr French's Site | Extension: Pre-University Material | |

Physics and Maths Tutor | Moments of Inertia (AQA 1) | Moments of Inertia MS (AQA 1) | A-Level Qs: overlapping content |

#### Rotational Equilibrium

Newton's First Law says that if the forces on an object are balanced (i.e. it is in translational equilibrium) then it will move at a constant velocity. The angular equivalent states that if the torques on an object are balanced (i.e. it is in rotational equilibrium) then it will move at a constant angular velocity.

## Video Lessons

Chris Doner | Rotational Equilibrium | IB Specific | ||||

Science Shorts | Rotational Dynamics Overview |

## Resources

IB Physics | Option B Notes (Core) | |||||

Mr. G | B.1 Teaching Notes | B.1 Student Notes | ||||

Physics and Maths Tutor | Engineering Definitions | Engineering Key Points | Engineering Detailed Notes | Rotational Dynamics Flashcards | A Level Resources - content slightly different |

## Questions

Dr French's Eclecticon | Moments of Inertia and Rotational Dynamics | Solutions 1 | Solutions 2 | Link to Dr French's Site | Extension: Pre-University Material |

#### Angular Acceleration Equations

There are 5 of these angular SUVAT equations.

## Video Lessons

Chris Doner | Rotational Kinematics | Rotational Dynamics | Rolling | IB Specific | ||

Khan Academy | Angular Motion Variables | Rotational N2L | ||||

Science Shorts | Rotational Dynamics Overview |

## Resources

IB Physics | Option B Notes (Core) | |||||

Isaac Physics | Angular Equations of Motion | Summary | Rotational N2L | Rotational Kinetic Energy | ||

Mr. G | B.1 Teaching Notes | B.1 Student Notes | ||||

Physics and Maths Tutor | Engineering Definitions | Engineering Key Points | Engineering Detailed Notes | Rotational Dynamics Flashcards | A Level Resources - content slightly different |

## Questions

Dr French's Eclecticon | Non Uniform Circular Motion | Non Uniform Circular Motion Solutions | Link to Dr French's Site | Extension: Pre-University Material | ||

Physics and Maths Tutor | Angular motion (AQA 1) | Angular motion MS (AQA 1) | Rotational Motion (AQA 1) | Rotational Motion MS (AQA 1) | A-Level Qs: overlapping content |

#### Conservation of Angular Momentum

As before, there is a rotational analogue to the Conservation of Momentum - the Conservation of Angular Momentum.

## Video Lessons

Chris Doner | Angular Momentum | IB Specific | ||||

Khan Academy | Angular Momentum | Rotational KE | Rolling Problems | |||

Science Shorts | Rotational Dynamics Overview |

## Resources

IB Physics | Option B Notes (Core) | |||||

Isaac Physics | Angular Momentum | Level 5/6 Beyond IB | ||||

Mr. G | B.1 Teaching Notes | B.1 Student Notes | ||||

Physics and Maths Tutor | Engineering Definitions | Engineering Key Points | Engineering Detailed Notes | Rotational Dynamics Flashcards | A Level Resources - content slightly different |

## Questions

Physics and Maths Tutor | Rotational KE (AQA 1) | Rotational KE MS (AQA 1) | Angular Work & Power (AQA 1) | Angular Work & Power MS (AQA 1) | A-Level Qs: overlapping content |

## Additional Resources

Once you are completely confident with your SUVAT and have had some practice, we can start looking at motion in two dimensions, projectiles.