Levers and mechanical advantage

Overview

The fulcrum, effort, load, effort arm and load arm, first-, second- and third-class levers at the elbow and ankle, mechanical advantage and its equation, a worked ankle calculation, and the trade-offs of each class.

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

   Name the five components of a lever system.

   Model answer

   A lever system has a fulcrum, an effort and a load. The effort arm and the load arm complete the system.

2. 2

   What are the fulcrum, effort and load in a lever of the body?

   Model answer

   The fulcrum is the joint about which the lever turns. The effort is the force from the muscle, and the load is the resistance being moved.

3. 3

   Define the effort arm and the load arm.

   Model answer

   The effort arm is the perpendicular distance from the fulcrum to the line of the effort. The load arm is the perpendicular distance from the fulcrum to the load.

4. 4

   How is a first-class lever arranged?

   Model answer

   A first-class lever has the fulcrum between the effort and the load. The lever works like a see-saw.

5. 5

   Which class of lever operates at the elbow as a netballer extends the arm to shoot?

   Model answer

   Extension of the elbow by the triceps uses a first-class lever. The elbow is the fulcrum, with the triceps effort behind it and the ball as the load.

6. 6

   How is a second-class lever arranged?

   Model answer

   A second-class lever has the load between the fulcrum and the effort. The effort arm is always longer than the load arm.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.