AQA · A-Level · Physical Education
Course version: 7582 · Version from Sept 2016
Three classes of lever and examples of their use in the body during…
Full specification wording
Levers: Three classes of lever and examples of their use in the body during physical activity and sport.
A lever is a rigid bar that rotates about a fulcrum when force is applied.
Checked against the AQA 7582 specification (opens in a new tab) on .
- Point 1 of 2
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A lever is a rigid bar that rotates about a fulcrum when force is applied. Its three parts are the fulcrum (pivot), the effort (force applied by a muscle) and the load (resistance to be moved). The relative positions of these parts define the class. First class: fulcrum between effort and load, as when the triceps apply effort at the elbow to extend the forearm against a load. Second class: load between fulcrum and effort, as when the calf muscles raise the heel during plantar flexion at the ankle. Third class: effort between fulcrum and load, as when the biceps flex the elbow to lift a mass. Most levers in the body are third class.
What earns the marks
- A lever has a fulcrum (pivot), an effort (force) and a load (resistance).
- First class lever: the fulcrum lies between the effort and the load.
- Second class lever: the load lies between the fulcrum and the effort.
- Third class lever: the effort lies between the fulcrum and the load.
- In the body the effort is provided by a muscle contracting and pulling on a bone.
- Most levers in the human body are third class, which favours speed and range of movement over force.
Common mistakes and how to put them right
Naming the class by the order in which the parts are listed rather than by which part lies in the middle.
Put it right: The middle component decides the class.
Assuming the load is always a weight.
Put it right: The load is any resistance, including body mass or an opponent.
Believing most body levers are first class.
Put it right: Most are third class because the muscle attaches close to the joint.
Confusing the fulcrum with the effort.
Put it right: The fulcrum is the joint about which the bone rotates, not the muscle.
Exam tips
- Sketch the lever and label fulcrum, effort and load before deciding the class.
- Use the middle component as a quick check: fulcrum middle means first class, load middle means second class, effort middle means third class.
- Give a named sporting action, such as elbow extension in a throw, to show the lever in use.
Try the lesson
The start of the Levers: Three classes of lever and examples of their use in the body during physical activity and sport. lesson, made from checked teaching notes for this specification point.
Have a go first
In the human body, which arrangement describes a first-class lever?
Listen
A lever is a rigid bar that rotates about a fulcrum when force is applied. Its three parts are the fulcrum (pivot), the effort (force applied by a muscle) and the load (resistance to be moved). The relative positions of these parts define the class. First class: fulcrum between effort and load, as when the triceps apply effort at the elbow to extend the forearm against a load. Second class: load between fulcrum and effort, as when the calf muscles raise the heel during plantar flexion at the ankle. Third class: effort between fulcrum and load, as when the biceps flex the elbow to lift a mass. Most levers in the body are third class. A strong answer earns marks for these points. A lever has a fulcrum (pivot), an effort (force) and a load (resistance). First class lever: the fulcrum lies between the effort and the load. Second class lever: the load lies between the fulcrum and the effort. Third class lever: the effort lies between the fulcrum and the load. Exam tip: Sketch the lever and label fulcrum, effort and load before deciding the class.
Key words
Say what each word means before you turn the card.
Lever systems in the body
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Fulcrum, effort and load
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Classes of lever
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See every definition
- Lever systems in the body
- A lever is a rigid bar that rotates about a fulcrum when force is applied, and its three parts are the fulcrum, the effort and the load.
- Fulcrum, effort and load
- The fulcrum is the pivot, the effort is the force applied by a muscle, and the load is the resistance to be moved.
- Classes of lever
- The relative positions of the fulcrum, effort and load define the class, and most levers in the body are third class.
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