Free GCSE Physics lesson: Force and Acceleration
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Free Lessons -> GCSE / Key Stage 4 -> Physics -> Force and Acceleration

Lesson 21 · GCSE / Key Stage 4 · Physics

Required practical: force and acceleration

Investigate how force and mass affect acceleration using trolleys, light gates or motion sensors.

Qualification: GCSE Subject: Physics Required practical Separate Physics and Combined Science

Practical skills

This lesson builds force, mass and acceleration practical for GCSE Physics.

Use the core lesson first, then match the exam-board guidance to your school route. Many pupils meet this content through Combined Science as well as Separate Physics.

Good forSeparate Physics and Combined Science
FocusForce, mass and acceleration practical
Time45-60 minutes
EquipmentTrolley, ramp or track, pulley, masses, light gates or motion sensor, ruler and calculator.
Paper fitSupports both papers through study, maths or practical skills
TierFoundation and Higher core
Practical linkRequired/core practical focus
Maths tagsM1 substitution with units, M6 ratio and percentage

What you will learn

  • Describe a method for testing F = m a.
  • Identify force, mass and acceleration variables.
  • Explain why friction and timing uncertainty matter.
  • Use graph evidence to support a conclusion.

Exam-board fit

RouteSeparate Physics and Combined Science
PaperSupports both papers through study, maths or practical skills
TierFoundation and Higher core
Specification fitPractical skills: Force, mass and acceleration practical
Practical linkRequired/core practical focus
Maths ladderM1 substitution with units, M6 ratio and percentage

Exact paper labels and specification-point numbering vary by board and cohort, so match this lesson to your school route before using past-paper questions.

Trolley investigation supplied on this page

Use the trolley and hanging mass examples to practise variable control and acceleration calculations.

Clear explanation

This practical investigates how acceleration changes when resultant force or mass changes. A trolley can be pulled by a hanging mass or driven by another controlled force.

If mass is kept constant, increasing resultant force should increase acceleration. If force is kept constant, increasing mass should reduce acceleration.

Friction, timing resolution and inconsistent release can affect results, so repeat readings and careful setup matter.

Key graph

Acceleration against resultant force graph An acceleration against resultant force graph is a straight line through the origin when mass is constant. resultant force / N acceleration / m/s² direct proportion
Graph: for constant mass, acceleration is directly proportional to resultant force.

Key diagram

Trolley, pulley and hanging mass apparatus for F = m a A trolley on a bench is attached over a pulley to a hanging mass, with light gates used to measure acceleration. trolley light gates hanging mass provides force
Diagram: the apparatus diagram links the measured acceleration to the changing force from the hanging mass.

Worked examples

Using F = m a

A 0.8 kg trolley accelerates at 1.5 m/s2.

F = m a

F = 0.8 x 1.5 = 1.2

Answer: The resultant force is 1.2 N.

Quick checks

Choose an answer, then check your thinking.

1. If mass stays constant, what should happen when resultant force increases?

2. Why are light gates useful in this practical?

Practice questions

Question 1

A 1.2 kg trolley has resultant force 3.6 N. Calculate acceleration.

Reveal answer and marking guidance

Answer: 3 m/s2.

Marking: Credit a = F ÷ m and 3.6 ÷ 1.2 = 3 m/s2.

Question 2

Name one control variable when testing force against acceleration.

Reveal answer and marking guidance

Answer: Mass of the trolley system.

Marking: Credit keeping total mass constant.

Question 3

Why repeat each run?

Reveal answer and marking guidance

Answer: To spot anomalies and calculate a more reliable mean acceleration.

Marking: Credit reliability and anomaly detection.

Question 4

What graph would support F = m a for constant mass?

Reveal answer and marking guidance

Answer: Acceleration against force should be a straight line through the origin.

Marking: Credit direct proportionality between force and acceleration.

Exam practice ladder

AO1 fluencyRecall the key definition, unit, equation or model before using the lesson questions.
AO2 applicationApply force, mass and acceleration practical to an unfamiliar device, practical setup or data description.
AO3 analysisUse evidence, graph features, uncertainty, method quality or conclusion wording where the question asks you to evaluate.
Maths skillM1 substitution with units

Answers and marking guidance

The exact practice answers are hidden under each question so you can try first. For this lesson, marks come from using the correct physics model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as transfer, resultant force, acceleration, evidence and uncertainty.

Common mistakes

  • Changing force and mass together without controlling either.
  • Ignoring friction on the track.
  • Using average speed as acceleration without change in velocity.
  • Not resetting the trolley position between runs.

Exam-board guidance

All supported routes assess the core physics idea, but they may group topics, practicals and paper wording differently.

AQA GCSE Physics

AQA GCSE Physics: use this lesson for force, mass and acceleration practical, then check whether your class is taking Separate Physics or Combined Science.

OCR GCSE Physics

OCR GCSE Physics: the core physics idea is shared, but Gateway and Twenty First Century may organise questions differently.

Pearson Edexcel GCSE Physics

Pearson Edexcel GCSE Physics: practise the concept, the equation use and the practical language because questions often connect them.

Eduqas GCSE Physics

Eduqas GCSE Physics: learn the core explanation and practise applying it to unfamiliar contexts, data and practical questions.

WJEC Wales

WJEC Wales: check whether your class is using the current GCSE Physics route or a newer science route, then use this lesson for the shared physics idea.

CCEA GCSE Physics

CCEA GCSE Physics: connect the idea to your unit and remember that practical skills are assessed directly.

Extension challenge

Design a results table for changing force while keeping total mass constant.

Reveal answer

Example answer: A strong extension response names the physics model, uses accurate units and explains why the evidence supports the conclusion.

Next lesson

Next, continue with Required Practical: Waves in a Ripple Tank.

Previous lesson: Resistance of a WireBack to GCSE Physics lessonsNext lesson: Required Practical: Waves in a Ripple Tank