B.1.4SL only
Levers in movement and sport
Guiding question: How does the arrangement of fulcrum, effort and load decide whether a lever favours force or speed?
Learn it, then try it
Read each idea, work through its activities, then tick it off. 0 of 1 done.
B.1.4.1
Classes of lever
The middle component sets the class: fulcrum for first class, load for second class and effort for third class. Second-class levers always give a mechanical advantage; third-class levers, the most common in the body, give a disadvantage but more speed and range. First-class levers can give either, depending on where the fulcrum sits. Implements such as rackets and bats lengthen the lever, so the end moves faster for the same angular velocity.
Explore
Build a lever
Pick a movement or drag the sliders. Watch how the order of fulcrum, effort and load sets the class, and how the arm lengths decide whether the lever favours force or speed.
Third class
Mechanical advantage = effort arm ÷ load arm = 15 ÷ 80 = 0.19
Mechanical disadvantage: the load arm is longer, so a large effort is needed, but the load moves fast through a large range.
In the body: The elbow is the fulcrum, the biceps insert close to it (effort) and the dumbbell in the hand is the load.
Remember it by the middle component: Fulcrum in the middle = 1st, Load = 2nd, Effort = 3rd ("FLE 1-2-3").
Sort it
Which class of lever?
Sort each movement into the class of lever acting at the named joint.
Tap an example, then tap where it belongs.
Check yourself
Quick check
1.Most levers in the human body are third class. What does this mean for movement?
2.A hockey player uses a longer stick. Assuming the same angular velocity at the shoulder, what happens to the end of the stick?
3.In a lever, the effort arm is 4 cm and the load arm is 30 cm. Which statement is correct?
Match the terms
Key terms
Match each term to its meaning.
Tap a term, then tap its meaning.
Practise this topic
Self-marking exam-style questions with Guide me hints and full mark schemes.
Links to other topics
- C.2.1How might changing the length of an external lever, such as a vaulting pole, affect learning a skill?