KVPY SX SB Exam 2012 Question Paper

Question : 24 of 120

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Seven identical coins are rigidly arranged on a flat table in the pattern shown below so that each coin touches its neighbours. Each coin is a thin disc of mass m and radius r. Note that the moment of inertia of an individual coin about an axis passing through center and perpendicular to the plane of the coin is

{mr^2}/2

The moment of inertia of the system of seven coins about an axis that passes through the point P (the centre of the coin positioned directly to the right of the central coin) and perpendicular to the plane of the coins is

$55/2mr^2$
$127/2mr^2$
$111/2mr^2$
$55 mr^2$

Validate

Solution:

By using parallel axis theorem,

I=111/2mr^2

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