Question

question 16 (1 point)
when is the average velocity of an object equal to the instantaneous velocity?
always
never
only when the velocity is constant
only when the velocity is increasing at a constant rate

Explanation:

To determine when average velocity equals instantaneous velocity, recall their definitions. Average velocity is the total displacement over total time ($v_{avg}=\frac{\Delta x}{\Delta t}$), and instantaneous velocity is the velocity at a specific instant (the limit of $\frac{\Delta x}{\Delta t}$ as $\Delta t$ approaches 0). If velocity is constant, the object’s speed and direction don’t change. So, at any instant, the velocity (instantaneous) is the same as the average velocity over any time interval (since displacement changes uniformly with time).

• "Always" is incorrect because if velocity changes (e.g., acceleration), average and instantaneous velocities differ (e.g., an object speeding up has a higher instantaneous velocity at the end of an interval than the average over that interval).
• "Never" is wrong because constant velocity is a valid case where they are equal.
• "Only when velocity is increasing at a constant rate" (constant acceleration) means velocity is changing, so average and instantaneous velocities won’t be equal throughout (e.g., a car accelerating from 0 to 10 m/s: average velocity over the interval is 5 m/s, but instantaneous velocity varies from 0 to 10 m/s).

Thus, the correct condition is when velocity is constant.

Answer:

C. only when the velocity is constant