Speed and Velocity
Speed is how fast an object moves, and velocity is its speed in a given direction.
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Speed is how fast an object moves, and velocity is its speed in a given direction.
- Speed equals distance over time
- Velocity changes if direction changes
- Average speed uses total distance and total time
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Speed and Velocity?
Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Speed and Velocity. 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 Speed and Velocity in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Speed and Velocity explains how the physical world behaves, from sport and transport to electricity and medicine.
Speed and Velocity in detail
Speed is how fast an object is moving, found as distance ÷ time, and is a scalar. Velocity is speed in a given direction, found as displacement ÷ time, and is a vector. A car going around a circular track at constant speed is continually changing velocity because its direction changes.
Average speed is total distance divided by total time, while instantaneous speed is the speed at a moment, such as a speedometer reading. Gradient of a distance-time graph gives speed. Typical values include walking at 1.5 m/s and sound at 340 m/s.
How the interactive helps you understand Speed and Velocity
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 Speed and Velocity.
Real-life uses and examples
- Explain everyday devices, such as brakes, lifts or chargers, using Speed and Velocity.
- Use Speed and Velocity to make sense of a practical and its results.
- Answer “explain” questions by linking Speed and Velocity to a clear cause and effect.
Common mistakes to avoid
- Forgetting that some quantities, such as force or velocity, also have a direction.
- Mixing up Speed and Velocity with a related quantity that has different units.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Speed and Velocity
What is Speed and Velocity?
Speed is how fast an object moves, and velocity is its speed in a given direction.
What are the most important points about Speed and Velocity?
The main points are: Speed equals distance over time; Velocity changes if direction changes; Average speed uses total distance and total time.
Why is Speed and Velocity useful?
Understanding Speed and Velocity explains how the physical world behaves, from sport and transport to electricity and medicine.
How can I practise Speed and Velocity?
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 Speed and Velocity?
Related topics in Physics include Free Fall and Gravity, Newton's Second Law, Friction.