AQA · A-Level · Physical Education
Course version: 7582 · Version from Sept 2016
Fluid mechanics: The Bernoulli principle applied to sporting situations.
Bernoulli's principle links a fluid's speed to its pressure: where air flows faster, its pressure falls; where it flows more slowly, pressure rises.
Checked against the AQA 7582 specification (opens in a new tab) on .
- Point 4 of 6
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Bernoulli's principle links a fluid's speed to its pressure: where air flows faster, its pressure falls; where it flows more slowly, pressure rises. In sport, asymmetric airflow creates a pressure difference that produces a force. This asymmetry can be caused by an object's shape, such as an aerofoil, or by spin. An aerofoil shape, like a discus or a Formula 1 car wing, forces air to travel faster over one curved surface, creating lower pressure and generating upward or downward lift. Alternatively, a spinning ball drags air with it; on one side, this rotation assists the airflow, increasing speed and lowering pressure, while opposing it on the other. This application of Bernoulli's principle to spinning objects is known as the Magnus effect, explaining the swerve of a curled football or sliced tennis ball.
What earns the marks
- States that faster-moving air has lower pressure and slower-moving air has higher pressure.
- Explains that asymmetric airflow can be created by an object's shape (aerofoil) or by spin (Magnus effect).
- Describes how an aerofoil shape causes air to travel faster over one surface, creating a pressure difference that generates upward or downward lift.
- Explains how a spinning object drags air, increasing air speed on one side and decreasing it on the other, creating a lateral or vertical force.
- Applies the principle to named sporting situations, such as a discus in flight, a Formula 1 car, or a curling football.
Common mistakes and how to put them right
Thinking faster air has higher pressure.
Put it right: The relationship is inverse, so faster flow means lower pressure.
Conflating Bernoulli's principle solely with spin.
Put it right: Asymmetric airflow can also be created by the aerofoil shape of an object, generating lift without rotation.
Confusing upward lift with downward lift.
Put it right: A discus generates upward lift for distance, whereas a racing car uses inverted aerofoils for downward lift to increase grip.
Exam tips
- Name the sport and the object, then state which side has faster air and which has lower pressure.
- Clearly distinguish between lift generated by an aerofoil shape and the Magnus force generated by spin.
- Use the chain: shape or spin causes different air speeds, different speeds cause a pressure difference, the pressure difference causes the force.
Try the lesson
The start of the Fluid mechanics: The Bernoulli principle applied to sporting situations. lesson, made from checked teaching notes for this specification point.
Have a go first
A football is struck so that it spins as it travels through the air. According to the Bernoulli principle, what happens to the air pressure on the side of the ball where the air moves faster?
Listen
Bernoulli's principle links a fluid's speed to its pressure: where air flows faster, its pressure falls; where it flows more slowly, pressure rises. In sport, asymmetric airflow creates a pressure difference that produces a force. This asymmetry can be caused by an object's shape, such as an aerofoil, or by spin. An aerofoil shape, like a discus or a Formula 1 car wing, forces air to travel faster over one curved surface, creating lower pressure and generating upward or downward lift. Alternatively, a spinning ball drags air with it; on one side, this rotation assists the airflow, increasing speed and lowering pressure, while opposing it on the other. This application of Bernoulli's principle to spinning objects is known as the Magnus effect, explaining the swerve of a curled football or sliced tennis ball. A strong answer earns marks for these points. States that faster-moving air has lower pressure and slower-moving air has higher pressure. Explains that asymmetric airflow can be created by an object's shape (aerofoil) or by spin (Magnus effect). Describes how an aerofoil shape causes air to travel faster over one surface, creating a pressure difference that generates upward or downward lift. Explains how a spinning object drags air, increasing air speed on one side and decreasing it on the other, creating a lateral or vertical force. Exam tip: Name the sport and the object, then state which side has faster air and which has lower pressure.
See it
Key words
Say what each word means before you turn the card.
Pressure and airflow
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Aerofoil shape and lift
Try answering aloud or in your head before turning the card.
Spin and the Magnus effect
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See every definition
- Pressure and airflow
- Where air flows faster its pressure falls, and where it flows more slowly its pressure rises.
- Aerofoil shape and lift
- A shape that forces air to travel faster over one curved surface, creating lower pressure and generating upward or downward lift.
- Spin and the Magnus effect
- A spinning object drags air with it, increasing speed and lowering pressure on one side while opposing it on the other, which is the application of Bernoulli's principle to spinning objects.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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