- #1
sankalpmittal
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Homework Statement
A metal rod of length 'L' and mass 'm' is pivoted at one end. A thin disk of mass 'M' and radius 'R' (<L) is attached at its centre to the free end of the rod. Consider two ways the disc is attached :
Case A: The disc is not free to rotate about its centre of mass, the geometrical centre.
Case B: The disc is free to rotate about its centre of mass, the geometrical centre.
The rod-disc system performs simple harmonic motion in vertical plane after being released from the same displaced position. Which of the following statements is/are true ?
1. Restoring torque in case A is greater than that in case B.
2.Restoring torque in case A is equal to that in case B.
3.Angular frequency in case A is more that that of B.
4.Angular frequency in case A is less that that of B.
(Visualize the diagram yourself.)
Homework Equations
The Attempt at a Solution
Option 2 should be correct because free body diagram of both the cases should be same.
I don't know how moment of inertia of a body is affected by its motion. I think that angular frequency should also be same (because moment of inertia of both cases of physical pendulums should be same) but answer key says its 2 and 4. How ?
Please help !
Thanks in advance..:)