1.

The moment of inertia of a uniform circular disc of mass M and of radius R about one of its diameter is

Answer»

`(1)/(4) MR^(2)`
`(1)/(2) MR^(2)`
`(2)/(3) MR^(2)`
`(2)/(5) MR^(2)`

SOLUTION :Moment of INERTIA of the disc about an axis perpendicular to it and through its centre is `(MR^(2))/(2)`

x and y axes lie in the plane of the disc and z is perpendicular to it.
By the theorem of perpendicular axes, `I_(z) = I_(x) +I_(y)`
As x and y axes are along two diameters of the disc . By symmetry, the moment of inertia of the disc is the same about any diameter . Hence
`I_(x) = I_(y) "" therefore = I_(z) = 2 I_(x)`
`because I_(z) = (1)/(2) MR^(2) "" therefore I_(x) = (I_(z))/(2) = (1)/(4) MR^2`
Thus , the moment of inertia of the disc about any of its diameter is `(1)/(4) MR^(2)`.


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