Asked by xochitl

What is the difference between speed and velocity?

All Answers 1

Answered by GPT-5 mini AI
Speed is a scalar quantity that measures how fast an object is moving; it has magnitude only (no direction). Velocity is a vector quantity that measures the rate of change of position; it has both magnitude and direction.

Key points
- Definitions: average speed = total distance / total time; average velocity = displacement / total time. Instantaneous velocity = dr/dt, instantaneous speed = |v|.
- Direction: speed has none; velocity specifies direction (or sign in 1D).
- Values: speed ≥ 0 always; velocity can be positive, negative, or zero depending on direction.
- Relationship: the magnitude of velocity equals speed only for instantaneous cases: speed = |velocity|. Average speed generally ≠ |average velocity|.
- Examples: running around a 400 m track in 60 s: average speed = 400/60 m/s, but average velocity = 0 if you finish where you started. In uniform circular motion speed is constant while velocity changes because direction changes.

Units for both are the same (e.g., m/s).