Rotational dynamics concept: What is the moment of inertia of a body? Choose the statement that best defines moment of inertia with respect to a specified axis; use this to identify its nature and dependence.

Difficulty: Easy

A vector equal to mass times angular acceleration
A scalar measure of rotational inertia about an axis, equal to Σ(mr²) for point masses
The torque needed to keep angular speed constant
The product of mass and linear velocity

Correct Answer: A scalar measure of rotational inertia about an axis, equal to Σ(mr²) for point masses

Explanation:

Concept and definition
Moment of inertia (I) quantifies a body's resistance to change in its angular velocity about a specified axis.For discrete masses: I = Σ m_i r_i²; for continuous bodies: I = ∫ r² dm.

Why scalar?
About a given axis, I is a scalar multiplier in τ = Iα (rigid body), analogous to mass in F = ma.

Common pitfalls
Confusing I with angular momentum (L = Iω) or torque.

Final Answer
A scalar measure of rotational inertia about an axis, equal to Σ(mr²) for point masses

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Rotational dynamics concept: What is the moment of inertia of a body? Choose the statement that best defines moment of inertia with respect to a specified axis; use this to identify its nature and dependence.

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