Thursday, 2 January 2014
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.
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