UNIT 7: MACHINES

UNIT 7: MACHINES

2.- Simple machines

Simple machines have few parts. They are very easy to use but there are many types of simple machines, they are only variations of the three more important ones: inclined planes, levers and pulleys.

2.1.-INCLINED PLANES

It is a ramp that let us raise and lower objects. It has three main parts:

- Lenght: It is the distance from the beginning to the end of the ramp.

- Height. It is the distance from the tallest part of the ramp to the ground

- Angle: It is the shape the ramp makes against the ground.

2.2.- LEVERS

It is a rigid bar that let us to exert (aplicar) force on a point of support and lift objects. Levers have got three parts:

-        Point of support (fulcrum) : it is where we place the rigid bar acting as a lever.

-        Force: the effort that we exert on the lever.

-        Resistance (load): It is the force made by the object we want to move.

Depending on when these parts are, levers can be first class, second class or third class.

2.3.- PULLEYS

A pulley is a wheel that turns on an axis with a rope that goes around a groove. We use it to raise and lower objects. Pulleys have three main parts

-        Axle. It is the centre part of a pulley. It has a hole that is the axis of the pulley when it turns.

-        Channel. It is the groove the groove the rope is in.

-        Hub. It is the main body of the wheel that joins the axle and groove.

Actvities Unit 7:     Simple Machines

1.- Complete the sentences.

_______________ , _________________ and _____________________________  are the most common simple machines.

2.-  Which parts can you find in a lever?

________________________________________________________ .

3.- Complete these sentences using the following words

            raise                high                bar               move               support

-          A lever is a rigid _________  that moves at a point of _______________.

-          An inclined plane lets you ______________ heavy things up to ___________ places.

-          A pulley lets you  _______________ objects easily.

4.-  Draw an inclined plane  and label its parts.

5.- Draw the three types of  lever and label their parts

6.-  Draw a pulley in your notebook and label the parts