Which concept transfers the moment of inertia from its centroidal axis to another parallel axis?

• A. Moment of axis theorem
• B. Transfer formula
• C. Parallel axis theorem
• D. B or C

Answer: (D)

Transferring the moment of inertia from a centroidal axis to a parallel axis is governed by the parallel axis theorem (Steiner's theorem). It states that the inertia about any axis parallel to the centroidal axis equals the centroidal inertia plus the mass times the square of the distance between the axes (I = I_centroid + m d^2). For area moments, the same form holds with the area replacing mass (I = I_centroid + A d^2). Some texts describe this as a transfer formula, since you “transfer” the inertia to the new axis. Because both names describe the same relationship, the option that includes either term is appropriate, which is why that choice is best. The term that isn’t a standard label for this concept isn’t used in typical explanations.