- Created by: luluirmiger
- Created on: 10-01-19 19:18
TYPES OF LEVERS
Fulcrum = the fixed point at which the lever turns or is supported. Also called the 'axis'.
Load = the weight or 'resistance' that the lever must to move
Effort = the force required to move the load. Also called the 'force'.
- First class: fulcrum midway between load and effort (e.g. line-out in rugby)
- Second class: load between fulcrum and effort (e.g. press up)
- Third class: effort between load and fulcrum (e.g. paddling in a kayak)
Mechanical advantage measures the efficiency of a leaver.
Mechanical advantage = effort arm / load (resistance) arm
Effort arm - the distance from the effort to the fulcrum
Load arm - the distance from the load to the fulcrum
TYPES OF LEVERS
- Flexion: decrease in the angle of bones at a joint. e.g. knee - before kicking a ball
- Extention: increase in the angle of bones at a joint. e.g. knee - whilst kicking a ball
- Abduction: movement of a bone or limb away from the midline of the body. e.g. arms & legs - outward star jump
- Adduction: movement of a bone or limb towards the midline of the body. e.g. arms & legs - inward star jump
- Dorsiflexion: movement at the ankle joint that flexes the foot upwards and decreases the angle. e.g. ankles - squat
- Plantar flexion: movement at the ankle joint that points the toes and increases the angle. e.g. ankles - jump
- Rotation: a circular movement around a joint/axis. e.g. shoulder - bowling in cricket
PLANES OF MOVEMENT AND AXES OF ROTATION
- Plane = an imaginary line that splits the body in two and depicts the direction of movement.
- Axis = an imaginary straight line through the body which it rotates around.