Question

A solid aluminum sphere of radius R has moment of inertia I about an axis through its center. What is the moment of inertia about a central axis of a solid aluminum sphere of radius 2R

Answer 1

I1 = 2/5 M1 R^2 for a sphere about its center

I2 = 2/5 M2 (2 R)^2 = 2/5 M2 R^ * 4 = 8/5 M2 R^2

Remember that M2 is greater than M1 by a factor 0f 2^3 = 8

Then I2 exceeds I1 by a factor of 32