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Conservatin of angular momentum at centre

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In this we cannot conserve angular momentum at centre .

asked May 3, 2017 in Physics Problems by koolman (4,286 points)
B asks if angular momentum can be conserved about P, which is not at the centre. I do not understand the significance of your comment.
Check out option C . To find that we have to conserve angular momentum at point P
Sorry I do not understand your difficulty. Your question says "We cannot conserve angular momentum at centre." Your comment mentions conserving AM at point P, not at the centre.
To solve option C they have conserve angular momentum at point P in the solution . My question is why we cannot solve it by conserving angular momentum at centre .
Try to write a solution conserving AM at the centre. You know what answer to expect, so you can check for yourself if it works.
Please be specify in what would like me to clarify in my answer.I think my answer is straightforward.thanks.
@Green My comment above is addressed to koolman.

1 Answer

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Best answer

We cannot since torque due to friction is nonzero about that point

answered May 3, 2017 by Green (564 points)
selected May 4, 2017 by koolman
But initially it is smooth
See when they have applied conservation of angular momentum have they taken into consideration velocity of COM of the body.No.when this is possible that the possible that the body can be assumed to be purely rotating about its bottommost point.it is only when it rolls without slipping which implies that the surface should be rough.
Sorry , I was confused .
Thanks for the explanation .
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