In the context of vectors, scalars, and displacement, how do speed and velocity differ?

• A. Speed is a vector that includes direction, while velocity is a scalar that has no direction.
• B. Speed is a scalar that describes how fast something moves, while velocity is a vector that includes both speed and direction.
• C. Speed and velocity are identical quantities as long as the motion is changing direction.
• D. Speed measures displacement per unit time, while velocity measures total distance traveled per unit time.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definitions of scalar and vector quantities. Scalars have only magnitude (size), while vectors have both magnitude and direction.
2. Step 2: Define speed as a scalar quantity that measures how fast an object is moving, regardless of its direction. It is calculated as the total distance traveled divided by the time taken.
3. Step 3: Define velocity as a vector quantity that describes the rate of change of displacement, including both magnitude and direction. It is calculated as displacement divided by time.
4. Step 4: Recognize that speed is always positive or zero, while velocity can be positive, negative, or zero depending on the direction of motion.
5. Step 5: Conclude that speed and velocity differ because speed ignores direction and only measures how fast an object moves, whereas velocity includes direction and describes how fast and in what direction the object moves.