Vectors vs. Scalars in Physics

Steps:

• Recall that scalars have only magnitude (size), while vectors have both magnitude and direction.
• Examine each option: mass is a measure of matter with only magnitude, so it's scalar.
• Weight is the force due to gravity, requiring both magnitude (strength) and direction (downward), making it a vector.
• Confirm by elimination: options A and B describe mass as scalar (correct for mass but misses the vector requirement), C mislabels weight as scalar.

Why D is correct:

• Weight is defined as a vector quantity because it follows the vector addition law for forces, with magnitude mg (m = mass, g = gravity) and direction toward Earth's center.

Why the others are wrong:

• A: Mass has only magnitude, so it's scalar, not matching the "both magnitude and direction" criterion.
• B: Identical to A; mass is scalar.
• C: Weight has direction, so labeling it scalar is incorrect.

Final answer: D