What is the formula for average acceleration?

• A. Time divided by velocity
• B. Change in velocity divided by time
• C. Velocity divided by time
• D. Mass times acceleration

Answer: (B)

Average acceleration is the rate at which velocity changes over a given time interval. It measures how quickly the velocity vector is changing, including both speed and direction.

The correct relation is ā = Δv / Δt, where Δv is the change in velocity and Δt is the time over which that change occurs. This formula captures not just how fast you’re moving, but how your motion is evolving during that interval. For example, if a car speeds up from 4 m/s to 10 m/s in 2 seconds, Δv = 6 m/s and Δt = 2 s, so ā = 3 m/s^2. The direction matters too, since Δv includes any changes in direction.

Velocity divided by time would not generally give acceleration, because it ignores how much the velocity actually changes during the interval. Mass times acceleration is F = ma, which relates to force, not the definition of average acceleration. Time divided by velocity is not a meaningful measure of how velocity changes.