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Mechanics

Cool goIITian

 Joined: 31 Jan 2008 Post: 49
13 Feb 2008 12:08:42 IST
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Rotational Mechanics
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Q consider an isoscles triangle plate of mass M and base L the angle at apex is 90. the apex lies at the origin and the base is parallel to X axis .
1] find the moment of inertia about z axis ( coming out or going into the plane of paper)
2] find the moment of inertia of the plate about to x axis

Cool goIITian

Joined: 7 May 2007
Posts: 47
13 Feb 2008 12:54:35 IST
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refer to the attached image
let k be mass per unit area k=2M/L*L as area = 0.5*L*L
take diff. element at root2*x from the origin
area of diff element = root2 * x * dx
dm= k* root2 * x * dx
R= BD= BLcos45= x/root2

I =  integral dm* R*R* over limits 0 to L

ANS= (1/2*root2)*M*L*L

New kid on the Block

Joined: 13 Feb 2008
Posts: 6
13 Feb 2008 14:04:29 IST
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Huh

Cool goIITian

Joined: 31 Jan 2008
Posts: 49
18 Feb 2008 15:48:41 IST
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method may be right but ans ins incorrect

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