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Moment of Inertia

Physics: AQA A Level, topic 11.1.1

Moments of Inertia

A moment of inertia is a measure of how much an object will resist turning.

Calculation

Calculation

  • The moment of inertia of an object is how much an object will resist turning. The equation for the moment of inertia is:
  • Moment of inertia = mass x (distance from the turning point)2^2
  • I=mr2I=mr^2
  • The total moment of inertia for a compound system is the sum of all the moments of inertia:
  • Itotal=Σmr2{I_{total}}={\Sigma}mr^2
A massive ring

A massive ring

  • A ring of radius R and total mass M has a moment of inertia equal to MR2^2.
  • Iring=MR2{I_{ring}}=MR^2

Test yourself on Moment of Inertia

  • What is the correct equation for the moment of inertia of a body?

  • What is the moment of inertia of a massive ring?

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