Third Class Third Class LeversLevers

By: Manyi, Daniel and EllaBy: Manyi, Daniel and Ella

What is a Third Class What is a Third Class Lever?Lever?

Definition: A lever where the Definition: A lever where the effort is located between the effort is located between the fulcrum and the load.fulcrum and the load.

A lever is in fact one of the simplest A lever is in fact one of the simplest mechanical devices ever created. All a mechanical devices ever created. All a lever basically is, is a type of beam, lever basically is, is a type of beam, stick or rod that helps to produce stick or rod that helps to produce useful movement. But what help is just a useful movement. But what help is just a single rod on its own? For a lever to single rod on its own? For a lever to become of use it requires something to become of use it requires something to pivot on, this is called the fulcrum in pivot on, this is called the fulcrum in many scenarios. Like all simple many scenarios. Like all simple machines, a lever makes a job easier and machines, a lever makes a job easier and in this case by lifting weight with less in this case by lifting weight with less effort.effort.

First Class Lever

Second Class Levers

Third Class Levers

Third Class levers are different from the others in that the effort is placed between the load and the fulcrum, and the effort must travel a shorter distance and be greater than the load.

Third Class Levers in Third Class Levers in Everyday Life….....Everyday Life….....

Effort

Fulcrum

LoadPower

Shovel

They even use Third Class Levers in the construction industry when they use power shovels to help dig up and move dirt.

In the example of someone lifting a weight the elbow would act as the fulcrum, and the weight would become the load. As you lift the weight your biceps contract, providing the effort that will then allow you to lift the weight easily.

Measuring Force and Measuring Force and workwork

To measure force: Force of Gravity = To measure force: Force of Gravity = (mass of the object) x (strength of (mass of the object) x (strength of earth’s gravitational field)earth’s gravitational field)

Formula: Fg= mgFormula: Fg= mg

To measure work: (Work in joules) = (force To measure work: (Work in joules) = (force in Newtons) x (distance in metres)in Newtons) x (distance in metres)

Formula: W= FdFormula: W= Fd

Tweezers: 0.001 kgTweezers: 0.001 kg

Rock: 1.3 kgRock: 1.3 kg

Broom: 0.5 kgBroom: 0.5 kg

Tongs: 0.015 kgTongs: 0.015 kg

Questions……Questions……1.1. Where is the effort located in a Where is the effort located in a

Third Class Lever?Third Class Lever?

Answer:Answer:

The effort in a third class lever is The effort in a third class lever is located between the fulcrum and located between the fulcrum and the loadthe load

2. Where is the 2. Where is the

Fulcrum on a Fulcrum on a broom?broom?

3. Where is 3. Where is the load the load located on located on a fishing a fishing rod?rod?

4. Where is 4. Where is the effort the effort when when someone someone lifts a lifts a weight?weight?

5. Give three examples 5. Give three examples of a third class of a third class lever……lever……

6. How are third class 6. How are third class levers different from other levers different from other levers?levers?

7. In what sport 7. In what sport are third class are third class levers used? When levers used? When is it used in that is it used in that sport?sport?

8. How are third class levers used in 8. How are third class levers used in the construction industry?the construction industry?

The EndThe End