a whel consists of a circular disc of radius 'a' with four circular holes, each of radius a/4. the centres of the holes form a square and each centre is at a distance a/2 from the centre of the disc. if m is the mass of the wheel after the holes have been punched in it, the moment of the wheel about its axis is ...... ?
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4 Answers
62this one is good (not as tough as it sounds!).. i will post the diagram.. then see if any of u can get this one....
62or i will rather post a hint
The Inertia is an additive quantity.
So what you could have done is to find the inertia of the whole disk and then take away the intertial of the 4 circular holes!
The old mass will be "Total area"/"Area after removing 4 holes" time Final Mass!
Similaryly find the Masss of the 4 "Holes"
then find the I of these holes by taking Parallel axis theorem!
I hope this helps.. any one to complete the final solution?
1can be done by considering density ??... i mean by taking density per unit area ... is it the only way to solve this ?
62yes u can unique.. it is basically the same..
I cant think of another decent method right now!