Acceleration
Acceleration is the rate at which velocity changes with time.
▶ Interact
Play with the controls to see the idea in action.
📘 Learn
Acceleration is the rate at which velocity changes with time.
- a equals change in v divided by time
- Measured in metres per second squared
- Slowing down is negative acceleration
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Acceleration?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Acceleration. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.
Check that you can explain Acceleration in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Acceleration explains how the physical world behaves, from sport and transport to electricity and medicine.
Acceleration in detail
Acceleration is the rate of change of velocity: a = (v − u)/t, measured in m/s². A positive value means speeding up in the direction of travel, and a negative value, deceleration, means slowing down. Because velocity is a vector, changing direction is also acceleration.
On a velocity-time graph, acceleration is the gradient and distance travelled is the area underneath. Everyday examples include a car pulling away at traffic lights (about 2 m/s²) and an object falling under gravity (about 10 m/s²). Newton's second law links acceleration to force.
How the interactive helps you understand Acceleration
Move the slope and y-intercept sliders. The line and its equation update, so you can see how the slope sets the steepness and the intercept sets where the line crosses the y-axis.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Acceleration.
Real-life uses and examples
- Predict what a ball, car or circuit will do with Acceleration before you do the calculation.
- Explain everyday devices, such as brakes, lifts or chargers, using Acceleration.
- Use Acceleration to make sense of a practical and its results.
Common mistakes to avoid
- Mixing up Acceleration with a related quantity that has different units.
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Acceleration
What is Acceleration?
Acceleration is the rate at which velocity changes with time.
What are the most important points about Acceleration?
The main points are: a equals change in v divided by time; Measured in metres per second squared; Slowing down is negative acceleration.
Why is Acceleration useful?
Understanding Acceleration explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Acceleration?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Acceleration?
Related topics in Physics include Projectile Motion, Newton's Third Law, Air Resistance and Terminal Velocity.