what does a lever consist of?
a pivot (fulcrum)
weight to be moved (resistance)
source of energy (effort or force )
How do levers work?
the bones act as levers the joints are the fulcrum, the effort is provided by the muscles and the resistance is weight of the body part that is being moved (against gravity normally)
what are the 3 types of lever?
1st class lever
2nd class lever
3rd class lever
what is the description of a first class lever?
the fulcrum is located in between the effort and the resistance
what is a sporting example of a first class lever?
head and neck extension and flexion and extension at the elbow
what is the description of a second class lever?
the resistance lies between the fulcrum and the effort
what is a sporting example of the second class lever?
plantar flexion at the ankle
what is the description of the third class lever?
effort lies between the fulcrum and the resistance
what is a sporting example of third class lever?
all other joints in the body, hip and knee extension and flexion and elbow flexion
what is the rhyme to remember the type of lever and middle component?
FRE 123
letter shows which one is in the middle eg: first class lever fulcrum is in the middle
mechanical advantage defintion
where the effort arm is longer than the resistance arm
mechanical disadvantage definition
where the resistance arm is longer than the effort arm
what does mechanical disadvantage or advantage depend on?
depends on the length of the effort and the resistance arm
what is the effort arm?
the name of the name given to the shortest perpendicular distance between the application of effort and the fulcrum
what is the resistance arm?
the shortest perpendicular distance between the fulcrum and the resistance
what does it mean if it has a mechanical advantage ?
this means the lever system can move a large load over a short distance, and requires little effort however has a small range of movement and it is difficult to generate speed and distance
what does it mean to have a mechanical disadvantage?
this means that the lever system cannot move as heavy a load but can do it faster, it also has a larger range of movement
what does a mechanical advantage do to a second class lever?
can generate much larger forces, has to lift the whole body weight
what does a mechanical advantage do to a first class lever?
large range of movement and any resistance can be moved quickly
what does a mechanical advantage do to a third class lever?
large range of movement and any resistance can be moved quickly
what does a mechanical disadvantage do to a second class lever?
slow with a limited range of movement
what does a mechanical disadvantage do to a first class lever?
cannot apply much force to move any object
what does a mechanical disadvantage do to a third class lever?
cannot apply much force to move any object
