Question

For a two rotor system, the length of one shaft(A) is twice the other(B), then what is the relation between the Mass moment of inertia of the shafts.

(a) 2I(A) = I(B)

(b) I(A) = 2I(B)

(c) I(A) = I(B)

(d) 2I(A) = 3I(B)

This question was posed to me by my college director while I was bunking the class.

Question is taken from Free Torsional Vibrations of a Two Rotor System topic in chapter Torsional Vibrations of Machine Dynamics

Answer 1

Correct option is (a) 2I(A) = I(B)

For explanation I would say: For a two rotor system, we have L(A)I(A) = L(B)I(B)

Now L(A)=2L(B)

Therefore, 2I(A) = I(B).