Which statement best describes the relationship between mass and rotational inertia?

Which statement best describes the relationship between mass and rotational inertia?

• A. Torque is the rotational analog of mass
• B. Linear momentum is the rotational analog of mass
• C. Moment of Inertia is the rotational analog of mass
• D. Angular velocity is the rotational analog of mass

Answer: (C)

Resistance to changes in rotational motion is described by the moment of inertia. In rotational dynamics, the equation τ = I α mirrors F = m a, so the moment of inertia plays the same role as mass in determining how hard it is to change the rotation. This is why mass matters for rotation: for a point mass, I = m r^2, so more mass or the mass being farther from the axis increases the rotational resistance. The other ideas mix up different roles: torque is what causes rotation (the rotational counterpart to force), linear momentum relates to angular momentum, and angular velocity is a rate, not a measure of inertia.

Resistance to changes in rotational motion is described by the moment of inertia. In rotational dynamics, the equation τ = I α mirrors F = m a, so the moment of inertia plays the same role as mass in determining how hard it is to change the rotation. This is why mass matters for rotation: for a point mass, I = m r^2, so more mass or the mass being farther from the axis increases the rotational resistance. The other ideas mix up different roles: torque is what causes rotation (the rotational counterpart to force), linear momentum relates to angular momentum, and angular velocity is a rate, not a measure of inertia.