The solid cylinder of length 80   cm and mass M has a radius of 20   cm . Calculate the density of…

The solid cylinder of length 80 cm and mass M has a radius of 20 cm. Calculate the density of the material used if the moment of inertia of the cylinder about an axis CD parallel to AB as shown in figure is 2.7 kg m2.

  1. 1.49×102 kg m-3
  2. 7.5×101 kg m-3
  3. 14.9 kg m-3
  4. 7.5×102 kg m-3

Solution

I=Mr22+ML24=ρπr2Lr22+ρπr2LL24

=ρπr2Lr22+L24

⇒ρ=Iπr2Lr22+L24

On putting the values, we get ρ=1.49×102 kg m-3.

Asked in: JEE Main 2021 (26 Aug Shift 2)

Practice more Rotational Motion questions on Aicharya