Moment of inertia of a music triangle

AI Thread Summary
The discussion focuses on calculating the moment of inertia of an equilateral triangle made of identical rods. It emphasizes the importance of using the parallel axis theorem rather than approximating the rods as point masses, which is not suitable for this type of problem. Participants express uncertainty about the application of classical mechanics principles, particularly regarding the center of mass. The conversation highlights the need for a proper understanding of moment of inertia in relation to mass distribution. Overall, the thread seeks clarity on the correct approach to solve the problem.
zheng89120
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Moment of inertia of a "music triangle"

Homework Statement



Find the moment of inertia about an axis thru the centre of mass, perpendicular to the plane of an equilateral triangle consisting of identical rods of length 'l' and mass 'm' connected at their ends.

Homework Equations



Classical mechanics, maybe centre of inertia theorem (or whatever its called)

The Attempt at a Solution



not sure, is it possible to "approximate" the three rods as three point masses?
 
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zheng89120 said:
...
is it possible to "approximate" the three rods as three point masses?
No. Not for a moment of inertia problem.

Use the parallel axis theorem.
 


Is moment of interia similar to moments of mass?
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »

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