Simple Machine






A simple machine is a device which produces work with one movement.   There are three main types of simple machines:  levers, inclined planes and wheels.

A lever is  a firm bar which turns around a fixed point.  All levers have three parts:

• Fulcrum or pivot   -   this can be anywhere on the length of the bar which allows the                                             bar to turn.
• Effort                     -    the part on the bar where the pushing or pulling is applied.
• Load                       -    the part on the bar that lifts any weight.

                                                             Types of Levers

There are three types of levers.

First Class Levers    -   the fulcrum or pivot is between the load and the effort.  Simple                                                      machines such as the crowbar, claw hammer and spoon are                                                            examples of this type of lever.

Second Class Levers -   The load and the effort are on the same side of the fulcrum or pivot.  

Third Class Levers  -     The effort is nearer to the pivot and it moves a shorter distance.

                                           Fishing rods are examples of this type of lever.

Examples of levers 

Classes of levers

INCLINED PLANES

An inclined plane is a flat surface with one end higher than the other.  Inclined planes are used to raise heavy load to higher levels using less effort.  The effort, however has to travel a greater distance than the load.  A staircase, ramp and a mountain road are examples of inclined plane.

         

Examples of inclined planes






Are Wedges Inclined Planes?

A wedge is a type of inclined plane.  Many tools we use everyday are wedgess.  A wedge has sloping sides.  It sometimes has a sharp edge.  Sometimes we use a wedge to hold doors in place preventing them from slamming.  This wedge is called a door chock.  Wedges are also used to open things or cut them in pieces.
                                                                                                                             
Examples of wedges

WINDING INCLINED PLANE

Steps are inclined planes.  Sometimes steps and stairways are straight and sometimes they are curved or winding. These are called winding inclined plane.

Examples

SCREWS

A screw is a winding inclined plane.  A screw is used to pull things together or push them apart.




Activity 1

1.      Cut a strip of paper 12cm long by 4 cm wide.
2.      Wrap the paper around your pencil.  You have made a screw.

Activity 2

Can you think of other objects which have winding inclined planes?

List 5 of them.

1.    _________________________________________
2.    ________________________________________-
3.    _________________________________________
4.    _________________________________________
5,    _________________________________________


WEDGE

A wedge is a type of inclined plane.  Many tools we use everyday are wedges.  A wedge has sloping sides.  It sometimes has sharp edge.  Examples of wedge are knife, axe, hoe and axe.

Click to read information on wedge.








PULLEY

             


A pulley is a simply macchine made with a rope, belt or chain wrapped around one or more grooved wheels.  It can also be called a wheel machine.

There are two types of pulley and they work in two different ways. 

1.  Fixed Pulley:          This type of pulley can change the direction of a force. In ordder for a fixed pulley to work, a downward force is applied.

2.  Movable Pulley:      This type of pulley can change the amount of force.  The movable pulley is attached to the object you are moving.  In order for this type of pulley to work, the force is applied up instead of down.


View video on pulley

   







Click to read information on inclined plane
















Click on the video below to watch.

Simple Machines game