Biomechanics

1
Biomechanics

• Levers

2
Levers

• Levers are rigid objects that turn about a fixed
  point called a fulcrum and to which a force is
  applied at two other points.
• The body is made up of levers in the form of
  bones with joints providing the fulcrum or axis
  point.
• The are three main elements of levers
• Axis or pivot point called the fulcrum
• A resistance load to be moved
• A force the action causing the load to move

3
Types of Levers

• There are three types of levers
• First Class lever Here the axis is located
  between the resistance and the point of force
  application. Eg see saw

Resistance
Force
4
Types of Levers

• Second Class Lever The axis is at the end of
  the lever, while the resistance is between the
  axis and force. Eg wheel barrow, bottle opener

Resistance
Force
5
Types of Levers

• Third Class Lever the axis is again at the end
  of the lever while the force is applied between
  the axis and resistance. Eg lifting a pen off a
  desk

Resistance
Force
6
Types of Levers
F
R
A
7
Types of Levers
What type of lever is this an example of?
Third Class Lever
8
Types of Levers
What type of lever is this an example of?
Third Class Lever
9
Types of Levers
What type of lever is this an example of?
First Class Lever
10
Levers in Sport

• The velocity is greater at the end of a long
  lever than a short lever. The greater the
  velocity at impact, the greater the momentum will
  be delivered eg full extension of arm during
  tennis serve.

11
Levers in Sport

• Changing the length of the lever will allow for
  greater acceleration. Consider a soccer kick.
  Initially the leg is bent, causing a shorter
  lever arm to generate more velocity. As the
  player is about to strike the ball the lower limb
  is straightened to increase the velocity of the
  foot

12
Questions on Levers

• A golfer buys longer clubs. What issues will
  arise as a result of using longer clubs?
• Why would a cricketer choke the handle of the
  bat?
• Why is it better to use a longer pole when pole
  vaulting?