Which equations do I need for motion and forces?

The core equations are average speed equals distance over time, acceleration equals change in velocity over time, force equals mass times acceleration (F = ma), weight equals mass times gravitational field strength (W = mg), and momentum equals mass times velocity (p = mv). You should know the SI unit for each quantity and be able to rearrange every equation.

How do I read a velocity-time graph in CCEA Physics?

On a velocity-time graph the gradient (slope) gives the acceleration and the area under the line gives the distance travelled. Split the area into rectangles and triangles, find each area, and add them. On a distance-time graph it is the gradient that gives the speed, and a horizontal line means the object is stationary.

What is terminal velocity?

Terminal velocity is the constant maximum speed a falling object reaches when air resistance has grown to equal its weight. The resultant force is then zero, so by Newton's first law the object falls at a steady speed. Before that, the object accelerates while weight is greater than air resistance.

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Motion and forces: study guide - CCEA GCSE Physics

A study guide to the motion and forces topic of CCEA GCSE Physics: speed, velocity and acceleration, motion graphs, Newton's laws, weight and terminal velocity, momentum and stopping distances, with the key equations and how each is examined.

Generated by Claude Opus 4.89 min readCCEA Unit 1Updated 2026-06-14

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this topic covers
How it is examined
The equations to recall
How to revise it

Motion and forces is the mechanics core of CCEA GCSE Physics Unit 1. It rewards confident equation work and clear graph interpretation, and the same equations come back in the energy and momentum questions.

What this topic covers

This topic moves from describing motion to explaining it with forces:

Speed, velocity and acceleration - scalars and vectors, and the equations $v = s/t$ and $a = (v - u)/t$ .
Motion graphs - speed from the gradient of a distance-time graph; acceleration from the gradient and distance from the area of a velocity-time graph.
Newton's laws - resultant force, the first law (constant motion unless a resultant force acts), $F = ma$ , and equal-and-opposite force pairs.
Weight and terminal velocity - the difference between mass and weight, $W = mg$ , free fall, and how air resistance leads to a constant terminal velocity.
Momentum - $p = mv$ and conservation of momentum in collisions and explosions.
Stopping distances and safety - thinking, braking and stopping distances and how safety features increase impact time to reduce force.

How it is examined

Expect short calculations using the equations above, graph questions that ask you to find a gradient or an area, and extended-answer questions on terminal velocity and on how safety features work. Many marks are awarded for correct substitution, units, and a clear method, so always show your working.

The equations to recall

Average speed: $\text{speed} = \dfrac{\text{distance}}{\text{time}}$ .
Acceleration: $a = \dfrac{v - u}{t}$ .
Newton's second law: $F = ma$ .
Weight: $W = mg$ .
Momentum: $p = mv$ .

How to revise it

Drill the equations. Practise rearranging each one and carrying SI units through every calculation.
Practise both graph types. Be clear that gradient means speed on a distance-time graph but acceleration on a velocity-time graph, where the area is the distance.
Rehearse the standard explanations. Write out the terminal-velocity stages and the momentum-and-time safety argument until they are automatic.
Use conservation of momentum carefully. Set positive and negative directions, then balance momentum before and after.
Attempt past-paper questions for your tier and mark against the official schemes.

Work through the linked dot points for full worked answers, common mistakes and exam-style questions on each part of the topic.

Sources & how we know this

CCEA GCSE Physics specification — CCEA (2017)