AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Students should be able to recall and apply this equation.
Full specification wording
Pressure in a fluid 1: Students should be able to recall and apply this equation.
The equation is p = F ÷ A, where p is pressure in pascals (Pa), F is the normal force in newtons (N) and A is the area in square metres (m²).
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 9 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
The equation is p = F ÷ A, where p is pressure in pascals (Pa), F is the normal force in newtons (N) and A is the area in square metres (m²). Recall means writing it from memory; apply means substituting values, rearranging and calculating. For example, a force of 200 N acting on 0.50 m² gives p = 200 ÷ 0.50 = 400 Pa. Rearranged forms are F = p × A and A = F ÷ p. One pascal is one newton per square metre (1 Pa = 1 N/m²). Keep units consistent and convert cm² to m² before substituting.
What earns the marks
- Recall the equation p = F ÷ A and state the meaning of each symbol.
- State the units: pressure in pascals (Pa), force in newtons (N) and area in square metres (m²).
- Substitute known values into p = F ÷ A and calculate the pressure.
- Rearrange the equation to F = p × A or A = F ÷ p when the question asks for force or area.
- Convert area from cm² to m² by dividing by 10 000 before substitution.
- Recognise that 1 Pa = 1 N/m² and use this to check unit consistency.
Common mistakes and how to put them right
Multiplying force by area instead of dividing.
Put it right by using p = F ÷ A.
Substituting area in cm² without converting.
Put it right by converting to m² first.
Rearranging incorrectly when finding force.
Put it right by multiplying pressure by area to give F = p × A.
Exam tips
- Write the equation from memory before substituting numbers, then rearrange only after writing the base equation.
- Check that the area is in m² and the force is in N before calculating pressure in Pa.
- Give the unit with every numerical answer and use standard form for very large or very small pressures.
Try the lesson
The start of the Pressure in a fluid 1: Students should be able to recall and apply this equation. lesson, made from checked teaching notes for this specification point.
Have a go first
Which equation relates pressure, force and area?
Listen
The equation is p = F ÷ A, where p is pressure in pascals (Pa), F is the normal force in newtons (N) and A is the area in square metres (m²). Recall means writing it from memory; apply means substituting values, rearranging and calculating. For example, a force of 200 N acting on 0.50 m² gives p = 200 ÷ 0.50 = 400 Pa. Rearranged forms are F = p × A and A = F ÷ p. One pascal is one newton per square metre (1 Pa = 1 N/m²). Keep units consistent and convert cm² to m² before substituting. A strong answer earns marks for these points. Recall the equation p = F ÷ A and state the meaning of each symbol. State the units: pressure in pascals (Pa), force in newtons (N) and area in square metres (m²). Substitute known values into p = F ÷ A and calculate the pressure. Rearrange the equation to F = p × A or A = F ÷ p when the question asks for force or area. A common slip: Multiplying force by area instead of dividing. Instead, using p = F ÷ A. Exam tip: Write the equation from memory before substituting numbers, then rearrange only after writing the base equation.
Key words
Say what each word means before you turn the card.
Pressure in fluids
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Recall and application of equations
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SI units and unit consistency
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Rearranging equations
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See every definition
- Pressure in fluids
- Pressure is calculated using p = F ÷ A, where F is the normal force in newtons and A is the area in square metres.
- Recall and application of equations
- Recall means writing the equation from memory; apply means substituting values, rearranging and calculating.
- SI units and unit consistency
- Pressure is in pascals (Pa), force in newtons (N) and area in square metres (m²); keep units consistent and convert cm² to m² before substituting.
- Rearranging equations
- The equation p = F ÷ A can be rearranged to F = p × A or A = F ÷ p when the question asks for force or area.
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