Chapter 10

Rotational Mechanics

Everything Newton taught us about pushing, rewritten for turning.

Rotation of rigid bodies about a fixed axis: angular kinematics, torque, τ = Iα, equilibrium, angular momentum and its conservation, rotational kinetic energy and power, moments of inertia, the parallel and perpendicular axis theorems, and rolling.

Start the chapter Read the whole chapter 9 lessons · about 110 min

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Lessons

01Rotation of a Rigid BodyEvery point goes round in a circle, and all of them share one angle. 11 min
02TorqueTurning effect depends on how hard, where, and in which direction you push. 11 min
03Torque Makes Things Spin Up: τ = IαTorque plays the role of force; moment of inertia plays the role of mass. 12 min
04Bodies in EquilibriumBalance the forces and balance the torques, and nothing moves. 14 min
05Angular Momentum & Its ConservationPull your arms in and you spin faster. Nothing outside had to push. 12 min
06Rotational Kinetic Energy, Work & PowerA spinning wheel stores energy in the motion of all its parts. 10 min
07Calculating Moment of InertiaAdd up mass times distance squared, one slice at a time. 15 min
08Parallel & Perpendicular Axis TheoremsTwo shortcuts that turn one known moment of inertia into many. 11 min
09Rolling: Rotation Plus TranslationThe bottom of a rolling wheel is momentarily at rest; the top moves twice as fast as the centre. 15 min