The correct statement is:

B. To determine the car's velocity, Tom needs to know both its speed and direction of motion.

Explanation:

• Speed is a scalar quantity that refers only to how fast an object is moving (magnitude of motion), regardless of the direction.
• Velocity, on the other hand, is a vector quantity, meaning it has both a magnitude (speed) and a direction. Knowing the direction is essential for distinguishing velocity from speed.

Why the other statements are incorrect:

• A: This describes acceleration, not speed. The rate of change of velocity over time is acceleration, not speed.
• C: If position values are increasing, it does not necessarily mean the velocity is positive. The direction matters; for example, if the car is moving in a negative direction but returning to the origin, the velocity could be negative even if position values increase.
• D: Average speed is found by dividing the total distance traveled by the total time taken, not multiplying them.

Would you like any further details or have any questions?

Related Questions:

1. What is the difference between average speed and instantaneous speed?
2. How do you calculate average velocity from a position-time graph?
3. How can you calculate the acceleration of the car if you know the velocity over time?
4. What happens to velocity if the direction of motion changes but the speed remains the same?
5. How can Tom use calculus to find the instantaneous velocity of the car?

Tip:

To calculate velocity, always remember that direction is key—it defines whether velocity is positive or negative, depending on the chosen reference frame.