Fiducia TogetherForces and motion
What makes things speed up, slow down or stay put. Newton's three laws in usable form.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
A force is a push or pull, measured in newtons. Resultant force is the overall force after adding them as vectors. Newton's laws: an object stays at rest or at constant velocity unless acted on by a resultant force; F = ma; and every action has an equal and opposite reaction.
Where it applies
GCSE physics and combined science.
How it works
Distinguish scalars (size only — speed, distance, mass) from vectors (size and direction — velocity, displacement, force). Acceleration is change of velocity over time, so an object moving at constant speed in a circle IS accelerating.
On a velocity-time graph, gradient is acceleration and area is distance.
How to use it in your work
State which law you are using — questions often ask for it by name.
For Newton's third law, the pair must act on DIFFERENT objects. "Weight and normal reaction on a book" is not a third-law pair, which is the classic trap.
Always draw the free-body diagram before calculating.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams. The subject song runs the topics in order.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Physics Song The GCSE physics specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.