Mi-5 Moment of Inertia
Published: Thursday 09 March 2006 - Updated: Wednesday 18 April 2007
Aim
To demonstrate the dependence of the moment of inertia on the distribution of mass with respect to the axis of rotation.
Apparatus
- Rotor with slideable masses on long light tube and drive pulley
- Thin string and weight
Diagrams
Click on pictures to enlarge.
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Description
With masses fixed at maximum R, show the (slow) angular acceleration of the sytem resulting from torque exerted by the tension in the string. Set masses at minimum R and repeat, showing much higher angular acceleration with (approximately*) the same torque.
*Note: Strictly speaking torque is not quite constant because of variation of string tension T=m(g-a), but, because b has been chosen <<Rmin, a<<g for all R's.