Question

Let $I_A$ and $I_B$ be the moments of inertia of two solid cylinders of identical geometrical shape and size about their axes, the first made of aluminum and the second of iron then:

• A. $I_A<I_B$
• B. $I_A=I_B$
• C. $I_A>I_B$
• D. The relation between $I_A$ and $I_B$ depends on the actual shape of the bodies.

Answer 1

The correct option is A $I_A<I_B$

Moments of inertia (MOI) is depend on geometrical shape and mass distribution of body about axis of rotation.

Here geometrical shape is identical so its depends on mass, density of iron is more than aluminum. Mass of iron is more than aluminum for same volume. So MOI of iron is more than MOI of aluminum.