Soc 20-Lever Flashcards
Lever
System of muscles and bones working together to bring about movement. When. You exercise your muscles pull on your bones, and your bones create movement,acting as levers
What are the 4 components of a lever?
1) Fulcrum - (or pivot) - the point around which the lever
rotates (joints).
2) Load - the force that is applied by the lever system
(resistance/ object).
3) Effort - a force that is applied by the user of the lever
system (muscles).
4) Lever arm - a rigid bar such as a bone.
What shape repersent each component?
Fulcrum - triangle
Load - square
Effort - arrow
Lever arm - flat rectangle
First class lever
First class lever
Fulcrum in the middle
Examples: Tricep dip / nodding your head
Work at a mechanical advantage
Second class levers
Second class lever
Load in the middle
Examples: Calf raises / using a wheelbarrow
Work at a mechanical advantage
Third class levers
Third class lever
Effort in the middle
Examples: Tricep dip / nodding your head
Work at a mechanical disadvantage
What does FLE stand for?
Fulcrum
Load
Effort
Describe a first class lever
E.g 1 - Ticep dip ===The elbow it the fulcrum which sits between the load (body weight)
and the effort applied by the tricep
E.g 2 - Nodding your head === The neck joint (atlas and axis) is the fulcrum which sits between the load head and the effort applied by the neck muscles
Describe a second class lever
E.g 1 - Calf raiser === The body weight (load) sits between the toes and the ball of the feet (fulcrum) and the gastrocnemuis muscles apply the effort by pulling the heal
E.g 2 - Lifing a wheelbarran === The weight on the wheelbarrow youre carrying is the load, which sits between the wheel (fulcrum) and the handle (effort)
Describe a third class lever
E.g 1 - Bicep curl === The effort is applied by the bicep , which is between the fulcrum at the elbow joint and the weight in your hands (load)
E.g 2 - using a Spade === The effort is applied by the foot (gastrocnemos), which is between the fulcrum at the handle and the weight of the soil (load)
What is a mechanical advantage?
Definition: A large load can be lifted with a relatively small amount of effort.
This happens when the output of the lever is greater than the input - the load is greater than the effort, so you are getting more out than you are putting in.
First and second class levers both work at a mechanical advantage.
What is a mechanical disavantage?
Definition: Third class levers cannot lift as heavy a load with the same amount of effort, due to the position of the effort and load from the fulcrum.
The input of the lever is greater than the output - the force you apply is greater than the load so you are putting in more than you are getting out.
Third class levers work at a mechanical disadvantage.
Mechanical Advantage vs Disvantage
Mechanical ADVANTAGE
Input < output
Mechanical DISAVANTAGE
Input > output
