Use turning effect and force per area
A moment is the turning effect of a force about a pivot and uses perpendicular distance. Pressure is force per unit area, so the same force can produce different pressures when the contact area changes.
GCSE Physics resources
AQA GCSE Forces
Moments, Levers and Pressure
A moment is the turning effect of a force about a pivot and uses perpendicular distance. Pressure is force per unit area, so the same force can produce different pressures when the contact area changes.
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The quick revision snapshot
A moment is the turning effect of a force about a pivot and uses perpendicular distance. Pressure is force per unit area, so the same force can produce different pressures when the contact area changes.
By the end, you should be able to…
- Explain use turning effect and force per area using precise physics language.
- Apply the relevant equations, diagrams or practical method to an exam-style situation.
- Use the mini quizzes and practice answers to identify and correct a misconception.
Core learning content
Learn the idea before you practise it
Start with this short teaching sequence for Moments, Levers and Pressure. Read the model, use the visual, then test your recall before moving into examples and exam practice.
Build the picture
A moment depends on perpendicular distance from the pivot, so moving the same force further out increases its turning effect. Pressure is force divided by area: a sharp heel or knife concentrates a force on a small area, whereas a wide snowshoe reduces pressure.
Use the right relationship
Choose a relationship because of the physical change in the question, not because it is familiar. Weight: W = mg (N, kg, N/kg). Newton’s second law: F = ma (N, kg, m/s²). Momentum: p = mv (kg m/s). Keep the unit next to each value while you substitute.
What a strong answer does
Mark the pivot or contact area, select the correct perpendicular distance or area and keep N, m and Pa units consistent. Before writing, underline the command word and identify the information that matters. Keep a calculation as equation, substitution and answer with unit; keep an explanation as a linked chain using because, so or therefore. Finish by checking that the final sentence answers the exact context in the question and that the number, direction or conclusion agrees with the evidence given.
Retrieval practice
Quick checks
Answer without looking back first. The feedback explains the model, so a wrong answer still helps you learn.
Mini quiz 1
Check the core idea
Mini quiz 2
Apply the model
Mini quiz 3
Use exam precision
Try it
Moments and pressure model
How can distance from a pivot or contact area change an outcome?
What to notice: the readout and written explanation remain available if you do not use the controls.
Worked examples
See the method being built
Cover the answer, attempt the method and then compare your physics language as well as the number.
Example 1 · Calculate moment
A 30 N force acts perpendicularly 0.40 m from a pivot. Find moment.
- Use moment = force × distance.
- Calculate 30 × 0.40.
- Give N m.
Show the answer
Moment = 12 N m.
Example 2 · Balance a beam
A 10 N weight is 0.30 m from a pivot. What force at 0.15 m balances it?
- Equate clockwise and anticlockwise moments.
- 10 × 0.30 = F × 0.15.
- Rearrange.
Show the answer
F = 20 N.
Example 3 · Calculate pressure
A 600 N person stands on 0.030 m². Find pressure.
- Use p = F/A.
- Calculate 600 ÷ 0.030.
- Give pascals.
Show the answer
p = 20 000 Pa.
Misconception clinic
Common wrong turns
Each of these is tempting because it sounds almost right. Replace it with the precise physics before you meet it in a question.
- Using distance along the lever instead of perpendicular distance.
- Using area in cm² with Pa.
- Mixing moment and force.
Independent practice
Exam-style questions
Use the working space first. Reveal the guidance only after you have committed to an answer, then improve the exact part that would gain the next mark.
1. State the SI unit of moment.
[1 mark]Show answer and marking guidance
N m.
2. State the SI unit of pressure.
[1 mark]Show answer and marking guidance
Pa (N/m²).
3. Explain why a longer spanner makes a nut easier to turn.
[3 marks]Show answer and marking guidance
It increases perpendicular distance, so the same force produces a larger moment.
4. A 100 N force acts 0.20 m from a pivot. Calculate moment.
[2 marks]Show answer and marking guidance
20 N m.
5. Explain why snowshoes reduce pressure.
[3 marks]Show answer and marking guidance
They spread the same force over a larger area.
6. State why distance must be perpendicular in a moment calculation.
[1 mark]Show answer and marking guidance
Only the perpendicular separation produces the turning effect.
Questions pupils ask
GCSE Physics FAQs
What is the key idea in Moments, Levers and Pressure?
Forces questions often hide a simple model inside a diagram. Draw the forces, find the resultant, then connect the resultant to the motion or deformation.
How should I practise Moments, Levers and Pressure?
Read the snapshot, attempt the worked examples without looking, complete the mini quizzes and then use the practice questions to check your wording and method.
Next step
Keep your revision moving
Physics sticks when you move between explanation, retrieval and application.