Levers and Lever Systems Flashcards

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Questions and Answers

What is a lever?

A rigid bar that is free to pivot, or rotate, on a fixed point.

What are lever systems?

The co-ordination of our bones and muscles, primarily to create human movement.

What are the two main functions of a lever system?

To generate muscular effort to overcome a given load and to increase the speed of a given movement.

What are the 4 components of a lever system?

Lever, fulcrum, effort, load. Signup and view all the answers

What is the lever?

Bone. Signup and view all the answers

What is the fulcrum?

Joint. Signup and view all the answers

What is the effort?

Muscular force. Signup and view all the answers

What is the load?

Weight or resistance. Signup and view all the answers

What is a first class lever?

A lever system in which the fulcrum lies between the effort and the load. Signup and view all the answers

What is a second class lever?

A lever system in which the load lies between the effort and the fulcrum. Signup and view all the answers

What is a third class lever?

A lever system in which the effort lies between the load and the fulcrum. Signup and view all the answers

What is the effort arm?

The distance between the fulcrum and the effort in a lever system. Signup and view all the answers

What is the resistance (load) arm?

The distance between the fulcrum and the load in a lever system. Signup and view all the answers

What is a mechanical advantage?

Mechanical advantage exists in a lever system when the effort arm is longer than the resistance arm enabling it to overcome heavy loads. Signup and view all the answers

What is a mechanical disadvantage?

Mechanical disadvantage exists in a lever system when the resistance arm is longer than the effort arm allowing the lever to move quickly. Signup and view all the answers

What is in the middle of a first class lever?

Fulcrum. Signup and view all the answers

What is in the middle of a second class lever?

Load. Signup and view all the answers

What is in the middle of a third class lever?

Effort. Signup and view all the answers

Give an example of where there may be more than one lever system operating at a joint.

When flexing the elbow (as in a bicep curl) and when extending the elbow (as in throwing the javelin). Signup and view all the answers

Where are the majority of movements in the human body operated by?

Third class levers. Signup and view all the answers

Give an example of a first class lever and define each component in relation to the example.

Extension of the neck when preparing to head a football: Effort = trapezius, Fulcrum = spine, Load = weight of the player's head. Signup and view all the answers

Give an example of a second class lever and define each component in relation to the example.

A dancer on tiptoe: Effort = gastrocnemius and soleus, Fulcrum = toe/metatarsals, Load = weight of the dancer. Signup and view all the answers

Study Notes

Lever Basics

A lever is a rigid bar that pivots on a fixed point known as the fulcrum.
Lever systems coordinate bones and muscles to facilitate human movement.

Functions of Lever Systems

Generate muscular effort to overcome loads.
Increase the speed of movements.

Components of a Lever System

Four main components: lever (bone), fulcrum (joint), effort (muscular force), and load (weight or resistance).

Diagram Notations

Lever is represented as a line.
Fulcrum is represented as a triangle.
Effort is represented as an arrow.
Load is represented as an arrow with a square.

Types of Levers

First Class Lever: Fulcrum is between effort and load.
Second Class Lever: Load is between effort and fulcrum.
Third Class Lever: Effort is between load and fulcrum.

Lever Arms

Effort arm: Distance between the fulcrum and the effort.
Resistance arm (load arm): Distance between the fulcrum and the load.

Mechanical Advantage and Disadvantage

Mechanical Advantage: Occurs when the effort arm is longer than the resistance arm, enabling the lever to lift heavy loads.
Mechanical Disadvantage: Occurs when the resistance arm is longer than the effort arm, allowing for quicker movement.

Lever Class Acronyms

First class: E F L (Effort-Fulcrum-Load).
Second class: E L F (Effort-Load-Fulcrum).
Third class: F E L (Fulcrum-Effort-Load).

Joint Movement Examples

Flexing the elbow during a bicep curl creates a third class lever system.
Extending the elbow while throwing a javelin utilizes a first class lever system.

Prevalence of Lever Types

The majority of movements in the human body are operated by third class levers.

Specific Lever Examples

First Class Lever Example: Neck extension to head a football.
- Effort: Trapezius muscle
- Fulcrum: Spine
- Load: Weight of the player's head
Second Class Lever Example: A dancer on tiptoe.
- Effort: Gastrocnemius and soleus muscles
- Fulcrum: Toes (metatarsals)
- Load: Weight of the dancer

Summary of Fulcrum and Lever Relationships

Joints act as fulcrums, enabling bones (levers) to rotate and create movement through muscular effort.

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Description

Explore the fundamentals of levers and lever systems with these flashcards. Learn about the definition, functions, and coordination of bones and muscles in human movement. Perfect for students studying biomechanics or physical education.