Lever Systems Flashcards
(17 cards)
what is a first class lever
the load and effort down are at opposite ends of the lever and the fulcrum is in the middle
what is a second lever
the fulcrum and effort up are at opposite ends of the lever and the load is in the middle
what is a third class lever
the fulcrum and load are at opposite ends of the lever and the effort up is in the middle
what is the load in a lever
the weight of something and is represented by a square
what is the effort in a lever
the force applied by the muscles and is represented by an arrow
what is the fulcrum in a lever
the joint where the lever arm pivots and is represented by a triangle
what are first class levers used in
elbow extension such as during a football throw-in
what are second class levers used in
plantar flexion and dorsiflexion at the ankle such as standing on your toes to jump
what are third class levers used in
elbow flexion such as lifting a weight, and flexion and extension at the shoulder, hip and knee
what is the lever arm
the bone or body part being moved about a joint and it is shown as a straight arm
what is the effort arm
the distance between the fulcrum and the effort
what is the load arm
the distance between the fulcrum and the load
what does the mechanical advantage of a lever measure
how efficient it is at moving heavy loads
why do second class levers have a high mechanical advantage
the effort arm is longer than the weight arm as a large load can be moved with a small effort
why do third class levers have a low mechanical advantage
the effort arm is shorter than the load arm as a small load requires a large effort to move
when do first class levers have a high mechanical advantage
if the fulcrum is closer to the load than the effort, whereas if the fulcrum is closer to the effort than the load it is a low mechanical advantage
how do you calculate mechanical advantage
mechanical advantage = effort arm / load arm
