Which of the following best describes the difference between $\mathrm{instantaneous speed}$ and $\mathrm{average speed}$?

• A. $\mathrm{Instantaneous speed}$ is always greater than $\mathrm{average speed}$ for any motion.
• B. $\mathrm{Average speed}$ is the speed at a particular instant, while $\mathrm{instantaneous speed}$ is the total distance divided by total time.
• C. $\mathrm{Instantaneous speed}$ and $\mathrm{average speed}$ are always equal for any type of motion.
• D. $\mathrm{Instantaneous speed}$ is the speed of an object at a specific moment in time, while $\mathrm{average speed}$ is calculated over a total time interval as the total distance traveled divided by the total time taken ($\frac{\mathrm{total distance}}{\mathrm{total time}}$).

Answer: (D)

Verified step by step guidance

1. Understand that instantaneous speed refers to the speed of an object at a specific moment in time. It tells you how fast the object is moving right now, not over a period.
2. Recognize that average speed is calculated over a time interval and is defined as the total distance traveled divided by the total time taken. Mathematically, it is expressed as \(\text{average speed} = \frac{\text{total distance}}{\text{total time}}\).
3. Note that instantaneous speed can vary at different moments, while average speed gives a single value representing the overall motion during the time interval.
4. Realize that instantaneous speed is not necessarily always greater or smaller than average speed; it depends on how the speed changes during the motion.
5. Summarize that the key difference is: instantaneous speed is a snapshot at one instant, whereas average speed is a summary over a duration, calculated by dividing total distance by total time.