Vector Quantities in Velocity Definition

Steps:

• Identify quantities in the statement: velocity, change in displacement, change in time.
• Classify each: velocity is a vector (has magnitude and direction); change in displacement is a vector (displacement is a vector quantity); change in time is a scalar (time lacks direction).
• Confirm via formula: velocity $v = \frac{\Delta \vec{s}}{\Delta t}$, where $\Delta \vec{s}$ is vector and $\Delta t$ is scalar.
• Count vectors: two (velocity and change in displacement).

Why C is correct:

• Velocity and change in displacement are both vectors by definition, as they involve direction in the formula $v = \frac{\Delta \vec{s}}{\Delta t}$.

Why the others are wrong:

• A: Incorrect, as two quantities (velocity, change in displacement) are vectors.
• B: Incorrect, misses that both velocity and change in displacement qualify as vectors.
• D: Incorrect, change in time is a scalar, not a vector.

Final answer: C