Soc 20 - Lever Systems Flashcards
What does a ‘lever’ refer to?
A system of muscles and bones working together to bring about movement.
What do your muscles do to your bones when exercising?
The muscles pull on the bones and the bones create movement which act as levers.
How many components does a lever structure have?
4 components
What are the four lever structure components?
The fulcrum, a load, an effort and a lever arm
What is the fulcrum?
It is a point around which the lever rotates (joints)
What is a load?
The force that is applied by the lever system. The load is the object you want to move (dumb bell with your arm)
What is an effort?
A force that is applied by the user of the lever system. Effort is supplied by your muscles
What is the lever arm?
A rigid bar such as a bone
How many classes of levers are there?
There are three classes of levers.
What are the three classes of levers?
First class, second class and third class lever
What is a first class lever?
Where the fulcrum is in the middle.
What is a second class lever?
Where the load is in the middle.
What is a third class lever?
Where the effort is in the middle.
What is an example of a first class lever in your body?
The joint between your skull and the first vertebrae
What is an example of a second class lever in your body?
Your heel joint
What is an example of a third class lever in your body?
Your elbow joint
What exercise is an example of a second class lever? Where are the lever systems
Calf raises. The load is the body weight. The ball of the feet is the fulcrum. The gastrocnemius is the effort
What is an example of a third class lever? Where are the lever systems?
Bicep curl. Load is weight in your hands. Effort applied by bicep muscle. Fulcrum is the elbow joint.
What is an example of a first class lever? Where are the lever systems?
Head a football. Fulcrum is the neck. Weight of head is load. Effort is from neck muscles
What are advantages of first class levers?
They are stable, strong and increasing the length of lever arm increases mechanical advantage
What are disadvantages of a first class lever?
They are slow and have limited flexibility
What are advantages of second-class levers?
They are stable, strong and increasing the length of lever arm increases mechanical advantage
What are disadvantages to second-class levers?
They are slow and have limited flexibility
What are advantages to third class levers?
They have fast movement, have large range of motion and increasing the length of lever arm increases mechanical advantage
What are disadvantages to third class levers?
The force applied must always exceed the load
