Lever Systems - PE Flashcards

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Questions and Answers

Label a diagram of a first class lever.

A first class lever has its fulcrum (joint) lying in between the effort (muscle) and the resistance (load that needs moving).

What does the fulcrum of a first class lever lie in between?

Effort (muscle) and resistance (load that needs moving)

What is a second class lever?

A second class lever has its fulcrum at one end and the effort at the other. The resistance is then in the middle of the effort and the fulcrum.

Name an example of a second class lever and when it would be used.

Ankle; ball of the foot would be the fulcrum, gastrocnemius is the effort, and the weight of the person would be the resistance; used by sprinters when exploding out of blocks. Signup and view all the answers

What is a third class lever?

A third class lever has its fulcrum at one end and the resistance at the other. The effort is then in the middle of the fulcrum and the resistance. Signup and view all the answers

Name an example of a third class lever and give an example of a sporting situation.

Elbow joint; elbow joint is the fulcrum, hand is the resistance and bicep pulling through is the effort; used in a tennis forehand. Signup and view all the answers

To which bones in the arm does the effort in the elbow's third class lever apply?

Radius and Ulna Signup and view all the answers

Name an example of a first class lever.

Neck when raising the head; neck muscles are the effort, neck itself is the fulcrum and weight of the head is the resistance. Signup and view all the answers

What are the 3 main components allowing the second class lever in the ankle to function?

The ball of the foot; the gastrocnemius; the weight of the person. Signup and view all the answers

What is effort arm?

The distance between the effort (muscle) and the fulcrum (joint). Signup and view all the answers

What is resistance arm?

The distance between the resistance (load that needs moving) and the fulcrum (joint). Signup and view all the answers

When flexion happens at the elbow, the effort arm is the distance between which two components?

The biceps and the elbow joint. Signup and view all the answers

In the elbow's third-class lever, how long is the resistance arm?

Very long Signup and view all the answers

State the mechanical advantage in first and third class levers.

First and third class levers have an effort arm that is shorter than the resistance arm. For first and third class levers, the effort arm ÷ resistance arm is less than 1. Signup and view all the answers

State the mechanical advantage in second class levers.

The effort is further away from the fulcrum than the resistance (effort arm longer than the resistance arm). Signup and view all the answers

Which activity is a second class lever ideal for?

Lifting heavy weights Signup and view all the answers

What is the mechanical advantage equation?

The mechanical advantage is equal to the effort arm divided by the resistance arm. Signup and view all the answers

Which levers have a mechanical advantage smaller than 1?

First class and third class levers Signup and view all the answers

What is the effort in a second class ankle lever?

The gastrocnemius Signup and view all the answers

Study Notes

Lever Systems Overview

Levers are classified into three types: first class, second class, and third class based on the arrangement of the fulcrum, effort, and resistance.

First Class Lever

Fulcrum is positioned between effort (muscle) and resistance (load).
Example: Neck raising the head; neck muscles act as effort, the neck as fulcrum, and the head's weight as resistance.
Mechanical advantage is less than 1; effort arm is shorter than resistance arm.

Second Class Lever

Fulcrum is at one end, with effort at the opposite end and resistance in the middle.
Example: Ankle during sprinting; ball of foot is fulcrum, gastrocnemius is effort, and body weight acts as resistance.
Ideal for lifting heavy weights due to longer effort arm compared to resistance arm.
Mechanical advantage is greater than 1; effort arm is longer than resistance arm.

Third Class Lever

Fulcrum is at one end; resistance is at the opposite end, and effort is in the middle.
Example: Elbow joint during a tennis forehand; elbow acts as fulcrum, hand as resistance, and bicep as effort.
Effort applies primarily to the radius and ulna bones in the arm.
Mechanical advantage is less than 1; effort arm is shorter than resistance arm.

Key Components of Levers

Effort Arm: Distance from the fulcrum to where the effort is applied (e.g., biceps to elbow joint in third class levers).
Resistance Arm: Distance from the fulcrum to where resistance is located (e.g., weight needing movement).
In the elbow's third class lever, the resistance arm is notably long.

Mechanical Advantage

Equation: Mechanical advantage = Effort arm ÷ Resistance arm.
First and third class levers tend to have a mechanical advantage of less than 1, making them less efficient than second class levers.

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Description

Test your knowledge of lever systems with this set of flashcards focused on physical education. Learn about first and second class levers, their definitions, and key components like the fulcrum, effort, and resistance. Perfect for students looking to enhance their understanding of mechanics in sports and fitness.