Which statement correctly describes scalar and vector quantities, with examples in motion?

• A. Scalar quantities have magnitude only; vector quantities have magnitude and direction. Example: speed is scalar; velocity is vector.
• B. Scalar quantities have direction; vector quantities have magnitude only.
• C. Both scalar and vector quantities have direction.
• D. Scalar quantities are described by units; vector quantities are not.

Answer: (A)

The key idea is whether direction matters for the quantity. Scalars have magnitude only, while vectors have both magnitude and direction. In motion, speed is a scalar because it tells you how fast you’re going but not where you’re headed. Velocity is a vector because it combines how fast with which direction. A car going 60 km/h is described by speed, but a car going 60 km/h north is described by velocity. The same distinction applies to distance versus displacement: distance is the total amount traveled (scalar), while displacement is how far from the start you are and in what direction (vector). This is why the statement is correct: it captures that scalars have magnitude only and vectors have magnitude plus direction, with speed versus velocity as the clear motion examples.