Which of the following statements correctly describes the physical quantity $speed$?

• A. $Speed$ is a scalar quantity because it can be $-$negative.
• B. $Speed$ is a vector quantity because it is always $+$positive.
• C. $Speed$ is a vector quantity because it always has a direction.
• D. $Speed$ is a scalar quantity because it does not have a direction.

Answer: (D)

Verified step by step guidance

1. Recall the definition of speed: it is the rate at which an object covers distance, regardless of direction.
2. Understand that speed is a scalar quantity, meaning it has magnitude only and no direction associated with it.
3. Note that speed is always a positive value or zero, since distance cannot be negative.
4. Contrast speed with velocity, which is a vector quantity because it includes both magnitude and direction.
5. Conclude that the correct description is: speed is a scalar quantity because it does not have a direction.