6. Levers Flashcards
What are lever systems?
The coordination of our bones and muscles, primarily to create human movement.
What are the functions of levers?
- to generate muscular effort to overcome a given load
- to increase the speed of a given movement
What are the components of a lever system?
- lever = bone
- fulcrum = joint
- effort = muscular force
- load = weight/ resistance
What is the structure of a lever?
- bones act as levers (rigid structures rotating around a fixed point)
- fixed joint = fulcrum
- muscles surrounding a joint create internal forces that move the bones they’re attached to
- when a muscle contracts, an effort is created
How does a lever work?
- if effort is large enough to overcome load, it will pull on lever to create movement
Describe a first class lever
- EFL
- fulcrum in middle
Example of a 1st class lever
extension of the neck when preparing to head a football
Describe a 2nd class lever
- ELF
- load in middle
- effort arm is really long
- mechanical advantage
Example of a 2nd class lever
ball of foot in take off phase of high jump -> vertically accelerates an athlete’s whole weight easily which is due to effort being further away from fulcrum than load
Describe a 3rd class lever
- FEL
- effort in middle
- load arm is really long
- mechanical disadvantage
What is the effort arm?
the distance from the fulcrum to the effort
What is the load arm?
the distance from the load to the fulcrum
What determines the significance of the effort or load?
the greater the distance of the effort or load from the fulcrum
What is mechanical advantage?
when the effort arm is much greater than the load arm
Which lever experiences mechanical advantage?
- second class lever to move large load with small effort
- however, efficiency is at small range of motion
