Third Class
Levers
By: Manyi, Daniel and Ella
What is a Third Class Lever?
Definition: A lever where the effort is
located between the fulcrum and the load.
A lever is in fact one of the simplest
mechanical devices ever created. All
a lever basically is, is a type of
beam, stick or rod that helps to
produce useful movement. But what
help is just a single rod on its
own? For a lever to become of use it
requires something to pivot on, this
is called the fulcrum in many
scenarios. Like all simple machines,
a lever makes a job easier and in
this case by lifting weight with
less 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 Everyday Life….....
Fulcrum
Effort
Power Shovel
They even use Third
Class Levers in the
construction industry
when they use power
shovels to help dig up
and move dirt.
Load
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
work
To measure force: Force of Gravity = (mass of the
object) x (strength of earth’s gravitational field)
Formula: Fg= mg
To measure work: (Work in joules) = (force in
Newtons) x (distance in metres)
Formula: W= Fd
Tweezers: 0.001 kg
Rock: 1.3 kg
Broom: 0.5 kg
Tongs: 0.015 kg
Questions……
1. Where is the effort located in a
Third Class Lever?
Answer:
The effort in a third class lever is
located between the fulcrum
and the load
2. Where is the
Fulcrum on a broom?
3. Where is the
load located on
a fishing rod?
4. Where is the
effort when
someone lifts a
weight?
5. Give three examples of a third
class lever……
6. How are third class levers
different from other levers?
7. In what sport are third class levers
used? When is it used in that sport?
8. How are third class levers
used in the construction
industry?
The End