JEE Main20204 Sep 2020Evening ShiftPhysicsRotational MotionActual
Consider two uniform discs of the same thickness and different radii R 1 = R and R 2 = α R made of the same material. If the ratio of their moments of inertia I 1 and I 2 , respectively, about their axes is I 1 : I 2 = 1 : 16 then the value of α is :
Options
- A2 2
- B2
- C2
- D4
Correct answer
C. 2
Step-by-step solution
Moment of inertia of disc is given by I = MR 2 2 = ρ πR 2 t R 2 2 I   α   R 4 I 2 I 1 = R 2 R 1 4 16 1 = α 4 α = 2