The moment of inertia of a spherical shell is I = mr²
If two spheres have the same moment of inertia, then
I₁ = I₂
m₁(r₁)² = m₂(r₂)²
Solve for the second mass:
m₂ = m₁ (r₁/r₂)²
Given m₁ = 1 kg, r₁ = 2 m, r₂ = 1m,
m₂ = (1 kg) (2 m / 1 m)² = 4 kg
I have an answer for 4 steps if that helps any..
1.Parenthesis
2.Exponents
3. Multiplication/division (whatever comes first)
4. Addition/subtraction (whatever comes first)
P-3
you just write it backwards
starting with 3