Which statement best differentiates velocity from speed?

• A. Velocity is a scalar quantity.
• B. Speed is a scalar quantity, velocity is a vector.
• C. Velocity has magnitude only.
• D. Speed includes direction.

Answer: (B)

The difference being tested is that speed carries no direction, while velocity includes direction. Speed is a scalar, meaning it has only magnitude—the “how fast.” Velocity is a vector, so it has both magnitude and direction—the “how fast and which way.” For example, a car moving at 60 km/h north has speed 60 km/h, but its velocity is 60 km/h toward the north. The idea that velocity is only magnitude or that speed includes direction isn’t correct, because velocity must specify direction while speed does not.