Grade 11 · Physics
Acceleration
Why it matters
The rate of change of velocity.
Core20m readingPrerequisite: Speed & Velocity
What is acceleration in physics?
Short answer
Acceleration is the rate at which velocity changes with time, a vector measured in metres per second squared (m/s²). It equals the change in velocity divided by the time taken: a = Δv / Δt. Because velocity has direction, an object accelerates when it speeds up, slows down, or changes direction — even at constant speed around a curve.
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Frequently asked questions
- Can something accelerate at constant speed?
- Yes. Velocity includes direction, so an object moving in a circle at constant speed is accelerating because its direction keeps changing.
- What are the units of acceleration?
- Metres per second squared (m/s²) — a change in velocity (m/s) per second.