lever systems

Components of a lever Classes of lever Mechanical Advantage Mechanical Disadvantage

lever arm

helps to produce movement

fulcrum

a pivot

the joint of the body from which the lever produces movement

load

the resistance (weight/mass) that the athlete is trying to move

body weight or external weight e.g. a dumbbell

effort

the force created by a muscle which is connected to the bone that is trying to move the load

first class movements

fulcrum in the middle

e.g. heading a ball in food - effort is the neck muscle, fulcrum is the neck joint, load is the head

second class movements

load in the middle

e.g. sprinting/jumping - the effort is the gastrocnemius, the load is the body weight, the fulcrum is the ball of the foot

third class movements

effort is in the middle

e.g. bicep curl - fulcrum is the elbow joint, he effort is the bicep, the load is the weight of the object being held

mechanical advantage

the lever can move a large load with relatively low effort

load arm is shorter than effort arm

move slowly, but lifting a heavier load

mechanical disadvantage

the lever can’t move as much load very fast

load arm is longer than effort arm

faster movements over a larger range

first class lever - mechanical…

can have a mechanical advantage or disadvantage

e.g. nodding head

second class lever - mechanical…

always mechanical advantage because the effort arm is longer than the load arm

e.g. rising onto ball of foot

third class lever - mechanical…

always mechanical disadvantage because the effort arm is shorter than the load arm

e.g. flexing the knee or elbow