A semicircular disc of mass M and radius R is free to rotate about its diameter. The moment of inertia of…

A semicircular disc of mass M and radius R is free to rotate about its diameter. The moment of inertia of semicircular disc about a line perpendicular to its plane through centre is
  1. 34MR2
  2. MR22
  3. MR23
  4. MR24

Solution

The moment of inertia of disc of radius R about its axis is

I=M'R22

where, M'= mass of complete disc =2M

I=2MR22

I=MR2   ...i

If I1 be the moment of inertia of semicircular disc about its. axis, then disc may be assumed as combination of two semi-circular parts,

Thus, I=I1+I1I1=I2=MR22

Asked in: BITSAT 2019

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