CM_3

JEE Advanced 2015 Questions › Mechanics questions › CM_3

What can be said about the CM of a uniform hemisphere without making any calculations ? Will its distance from the centre be more or less than r/2 ?

#Physics #Mechanics

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7 Answers

106

Asish Mahapatra ·2009-05-14 20:46:57

For a uniform hemisphere:
try to imagine the mass distribution.

It is more at the bottom half of the hemisphere as compared to the top half.
Hence the distance of COM of the hemisphere will be less than r/2

:ignore that 2R/pi it shud be 3R/8

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11

Gone.. ·2009-05-14 20:49:02

o ya !!
thanks !

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106

Asish Mahapatra ·2009-05-17 23:41:45

but for a hemispherical shell the COM is at R/2 though. Can you reason this out logically? i cant [2]

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Gone.. ·2009-05-19 22:36:20

how is that possible..ur 1st reason is fully right.. who told u it is at R/2 ??

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106

Asish Mahapatra ·2009-05-20 00:56:48

i calculated it..

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deepanshu001 agarwal ·2009-05-20 01:54:54

yep it is r/2 for sure.....

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Gone.. ·2009-05-20 10:40:02

but logically it seems impossible..

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