Which of the following best describes the difference between $speed$ and $velocity$?

• A. $Velocity$ is always greater than $speed$ for any moving object.
• B. $Speed$ and $velocity$ are both scalar quantities and only differ in their units.
• C. $Speed$ is a scalar quantity that measures how fast an object moves, while $velocity$ is a vector quantity that measures both the $speed$ and direction of an object's motion.
• D. $Speed$ measures the change in displacement, while $velocity$ measures the total distance traveled.

Answer: (C)

Verified step by step guidance

1. Understand that speed and velocity are both measures related to how fast an object is moving, but they differ fundamentally in their definitions and properties.
2. Recall that speed is a scalar quantity, which means it only has magnitude (how fast an object is moving) and no direction.
3. Recognize that velocity is a vector quantity, meaning it has both magnitude (speed) and direction, describing how fast and in which direction the object is moving.
4. Note that speed is calculated as the total distance traveled divided by the time taken, while velocity is calculated as the displacement (change in position) divided by the time taken.
5. Conclude that the key difference is that speed does not consider direction, whereas velocity includes direction, making velocity more informative about the motion of an object.