The three orders of lever in the body

Overview

The components of a lever, first-, second- and third-order levers and how to identify them, and the levers at the neck, elbow, ankle, knee, hip and shoulder in sporting actions.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What are the three components of a lever system?

   Model answer

   A lever system has a pivot or fulcrum, an effort and a load or resistance. Bones act as levers and joints act as pivots in the body.

2. 2

   In a body lever, what provides the effort and what provides the load?

   Model answer

   The effort comes from a contracting muscle pulling on the bone. The load is the weight of the body part plus anything it moves.

3. 3

   What is a first-order lever?

   Model answer

   A first-order lever, also called a first-class lever, has the pivot between the effort and the load. A see-saw is the everyday example.

4. 4

   What is a second-order lever?

   Model answer

   A second-order lever has the load between the pivot and the effort. A wheelbarrow is the everyday example.

5. 5

   What is a third-order lever?

   Model answer

   A third-order lever has the effort between the pivot and the load. Most joints in the body work as third-order levers.

6. 6

   How can the order of a lever be identified quickly?

   Model answer

   Find which component sits in the middle. A pivot in the middle means first order, a load means second order and an effort means third order.

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The same content, four other ways.

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Six ways to work the same material.