A uniform circular disc of mass 1000 g and radius 5 cm rotates about an axis passing through its centre and perpendicular to its plane. Its moment of inertia is
A
1.25 × 10⁻² kg m²
B
0.125 × 10⁻² kg m²
C
12.5 × 10⁻² kg m²
D
1250 × 10⁻² kg m²
Correct Option:
B
Explanation
For a uniform disc about an axis through its centre and perpendicular to its plane, I = 1/2 MR². Here M = 1000 g = 1 kg and R = 5 cm = 0.05 m. Therefore I = 1/2 × 1 × (0.05)² = 0.00125 kg m² = 0.125 × 10⁻² kg m².
