Mass Measures Inertia

Steps:

• Define mass as the quantity of matter in an object, which determines its inertia.
• Evaluate options against this definition: inertia resists changes in motion (Newton's first law).
• Eliminate A and D, as they confuse mass with gravitational effects.
• Confirm C matches inertia directly; discard B, unrelated to collisions.

Why C is correct:

• Mass is defined as the measure of an object's inertia, the resistance to acceleration per Newton's second law (F = ma).

Why the others are wrong:

• A: Describes weight, the gravitational force (weight = mg).
• B: Describes momentum (p = mv), not inherent mass.
• D: Balances measure mass by comparing weights, but weight is the force, not mass itself.

Final answer: C