Physics 11 · Physics · Lesson 2.2
Acceleration
- Level
- Grade 11
- Reading time
- 11 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
The rate of change of 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.
Concept preview
What you will be able to do
- 01Define acceleration as the rate of change of velocity
- 02Calculate acceleration from a change in velocity over time
- 03Interpret the slope and area of a velocity–time graph
So far we can describe where something is (position) and how fast it's going (velocity). But almost nothing in the real world moves at a steady velocity — cars speed up, balls fall faster and faster, brakes slow you down. So we need one more idea: how quickly the velocity itself is changing. That's acceleration — and it's the quantity you literally feel when a car floors it and presses you back into your seat.
School Plan
Acceleration
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Related topics
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.