1. Lever mechanisms
Department of Biology, WCU

2. Introduction Lever, fulcrum, force Bone, joint, muscle
Load is object or structure
Function
move load for effort
force
fulcrum
load
lever

3. Lever types 1. Power levers Characteristics e.g. standing on toes
Load close to fulcrum
Effort far from fulcrum
e.g. standing on toes

4. Lever types 2. Speed levers Characteristics e.g. pitching a baseball
Load far from fulcrum
Effort near fulcrum
e.g. pitching a baseball

5. Lever classes Characteristics First class levers
position of effort, fulcrum and load
First class levers
load, fulcrum, force

6. First class levers 1. power levers 2. speed levers
mechanical advantage
e.g. head extension
2. speed levers
mechanical disadvantage
e.g. tricep extension of forearm

7. Second class levers Characteristics fulcrum, load, force uncommon
all power levers
e.g. stand on toes

8. Third class levers Characteristics fulcrum, force, load
all speed levers
most common
e.g. flexion of forearm

9. Conclusions Speed have little power, power have slow speed
Difference among lever classes
fulcrum, force, load
Affect
speed of contraction
range of movement
weight lifted