A stone of mass 10 kg has a rotational inertia of 2.4 kg · m² about an axis A parallel to an axis through the center of mass. If axis A is 0.20 m from the center of mass axis, the rotational inertia about the center of mass axis is A) 0.40 kg · m². B) 2.0 kg · m². C) 2.4 kg · m². D) 2.8 kg · m². E) 4.4 kg · m².

Question

Quizplus · Accepted Answer

According to the parallel-axis theorem, the moment of inertia about the center of mass axis is given by $I_{cm} = I_A + Md^2$, where $I_A$ is the moment of inertia about axis A, $M$ is the mass of the object, and $d$ is the distance between the two axes. Substituting the given values, we get:

$I_{cm} = 2.4 + (10)(0.20)^2 = 2.0	ext{ kg}·	ext{m}^2$

Therefore, the correct choice is B.

A Stone of Mass 10 Kg Has a Rotational Inertia