Vectors Have Magnitude and Direction

Steps:

• Recall that vectors possess both magnitude and direction, while scalars have only magnitude.
• Classify quantities: velocity (displacement over time) and acceleration (change in velocity over time) require direction.
• Check options: identify pairs where both are vectors.
• Select the pair that matches both as vectors.

Why D is correct:

• Velocity and acceleration are vectors, as defined by their dependence on direction (e.g., velocity $\vec{v} = \frac{\Delta \vec{x}}{\Delta t}$, acceleration ).

Why the others are wrong:

• A: Length is a scalar (magnitude only); acceleration is a vector.
• B: Distance is a scalar (total path length); velocity is a vector.
• C: Both length and distance are scalars (no direction).

Final answer: D