3 rd Class Levers

1. 3rd Class Levers Sammie.H, Teah & Brooke

3. Definition in own words: Definition: A third class lever is the force between the fulcrum and the resistance force. It is the effort force behind the movement. A third class lever is the effort force that is applied between the fulcrum and the resistance force.

4. Example of 3rd Class Lever in Sport: • http://www.youtube.com/watch?v=b416sid8t6w • 3rd class levers are used when weight lifting. • They are used to apply force when lifting an object (eg: weights). • The force is applied at the insertion of the bicep between the weight and the fulcrum.

5. The Importance of 3rd Class levers: • Most movements in the human body are created by 3rd class levers. • 3rd class levers are important because as shown in the example in the video the bicep insertion is the 3rd class lever and is a very important part of weight lifting. With out that 3rd class lever then the weight would have not been able to be lifted. • The longer the lever the greater the speed at the end of the lever (eg: tennis because the racket adds length resulting in greater speed and force).

6. Questions and Answers: • A lever is basically a rigid structure, hinged at some point and to which forces are applied at two other points. • A lever consists of three basic parts: The Load (object/weight), the fulcrum and the force/effort. • The arrangement of these parts determines what class of lever it is and what it is designed to do. Consider a crowbar and a golf club. Their purposes levers provides us with the two main functions of levers. They are: • Crowbar – a crowbar is designed to move a resistance with a small input of force i.e. move a resistance. • Golf club – a golf club is designed to generate high velocities at one end that can be passed on to another object, i.e. velocity and momentum.

7. Questions and Answers: • Much of what we use in sport relates to the second point. Longer levers (within reason), generate the greatest velocity at the end. Consider the person swinging a golf club. In a golf swing, all parts of the club have to move through the same angle in the same amount of time. Because the club head has to travel a much greater distance than the hands in the same amount of time, it has to have a greater velocity. This is shown as the distance covered at “A” compared to “B”. This is the point of sticks, clubs, bats and racquets. • Does this mean that a golf club that was slightly longer than normal would give greater head speed? Yes it would. It assumes, of course, that the musculature of the player can generate and cope with the forces required. • When considering the overarm serve in volleyball or a smash in badminton, why do we want the point of contact to be at full arm extension? So we strike with as long a lever as possible that is moved through as wide a range of motion as possible. Hand/racquet will have more velocity.