❌Levers Flashcards
What are the three main components of levers?
Pivot - Fulcrum
Weight to be moved - Resistance
Source of energy - Effort/force
What is a fulcrum?
The point which the lever rotates
What is the resistance?
The weight to be moved by the lever system.
What is the effort?
The force applied by the user (muscle) of the lever system.
What’s an example of levers?
The skeleton forms a system of levers that allows us to move.
The bones act as the levers, the joints are the fulcrums, the effort is provided by the muscle and the resistance is the weight of the body part that is being moved (often against the force of gravity).
What are the types of levers?
First class Second class Third class
What are first class levers?
The fulcrum lies between the effort and resistance
What are second class levers?
The resistance is between the fulcrum and effort.
What are third class levers?
The effort is between the fulcrum and the resistance.
What does FLE, 123 mean?
1 - F (first class levers have the fulcrum in the middle) 2 - L (second class levers have the load/resistance in the middle) 3 - E (third class levers have the effort in the middle)
What’s an example of a first class lever?
The movement of the head and neck during flexion and extension.
Extension of the elbow
What’s an example of a second class lever?
There is only one example: Plantarflexion of the ankle.
What is an example of a third class lever?
Every other joints in the body.
Hip, knee and elbow flexion.
What is the effort/force arm?
The length of the line between where the fulcrum and effort are labelled.
What is the resistance arm?
The length of the line between where the fulcrum and the resistance are labelled.
What is mechanical advantage?
Where the force arm is longer than the resistance arm.
What is mechanical disadvantage?
Where the resistance arm is longer than the force arm.
What does mechanical disadvantage mean?
The lever system cannot move as heavy a load but can do it faster.
It also has a large range of movement.
What does mechanical advantage mean?
The lever system can move a large road over a short distance and requires little force.
It has a small range of movement and it is difficult to generate speed and distance.
What lever has the longest effort arm?
Class 2 because it has the most to overcome.
Body weight is in the middle.
What’s a sporting example of a first class lever?
A line out throw in rugby.
F = elbow joint L = ball (in hands) E = triceps
What’s a sporting example of a second class lever?
Point in ballet/gymnastics - plantarflexion
F = toes L = body weight E = gastrocnemius
What’s a sporting example of a third class lever?
Bicep curl - Flexion at the elbow.
F = elbow joint L = weight E = biceps
What lever have a high mechanical advantage?
Second class - has to lift the whole body weight. Can generate much larger forces.
What lever has a mechanical disadvantage?
Third class - always
First class - tends to have
