Machines used in everyday life

We introduced you to simple machines in a previous article. This week, we bring you more details about machines which make our life simpler.

A screw can also be categorised as a simple machine that can be used to hold things together. This is really

 like an inclined plane wrapped around a rod. You can notice this by wrapping a piece of paper, shaped like an inclined plane, around a pencil.

Screws are often used to hold two pieces of wood or metal together. When you open or close bottles, you use screws. The lid of a jar is a large, flat screw. Ridges inside the lid are screw threads that hold the lid to the jar.

Have you seen spiral-shaped stairways? That is screws being used in another way. The straight stairway would be very steep and hard to climb. The curved stairway is longer, but easier to climb.

The steering wheel of a vehicle is the best example of the wheel and axle. There, the wheel is connected to a rod called the axle. This is a simple machine that helps to steer a car.

A door knob is also a wheel. It connects to an axle that fits through the door. When you turn the wheel, the axle turns. The axle moves another part that opens the door. If the wheel falls off, you can still turn the axle. But it takes more force to turn just the axle than to turn the wheel.

In order to get water from a well, it is easier to use a simple machine called a pulley. A pulley is a wheel, usually with a grooved rim and is fixed at the top of the well. It holds a rope to one end of which a bucket is attached.

When you pull it from the other end of the rope, the bucket rises. If there was no pulley, you will have to make a greater effort to pull the heavy water-filled bucket from the well. There are also instances where people use movable pulleys. This will make the work easier.

As explained here, a lot of simple machines are found and used in our everyday life.

These make life a lot easier for us, human beings.

* Simple machine - one of six basic tools that helps us to work.

* Lever - A simple machine made of a bar that is supported at a point and turns on that point.

* Fulcrum - A point on which a lever is supported and around which it turns.

* Inclined plane - A flat surface with one end placed higher than the other.

* Wedge - Used to cut or split something.

* Screw - An inclined plane wrapped around a rod.

* Wheel and axle - Made of a rod connected to the centre of a wheel.

* Pulley - Made of a wheel, usually with a grooved rim, that holds a rope.

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How to use... A compass

Do you know what a compass is used for? It is used to find directions. A compass is a small, thin magnet that swings freely, like a spinner in a board game; one end of the magnet always points north. This end is the magnet's north pole. Do you like to check if a compass is working?

(1) Place the compass on a surface that is not made of magnetic material, such as a wooden table.

(2) Find the magnet's north pole. The north pole is specially marked, usually in colour or with an arrowhead.

(3) Take note of the letters N,E,S and W on the compass. These letters stand for the directions, North, East, South and West. When the magnet stops swinging, turn the compass so that N lines up with the north pole of the magnet.

(4) Repeat this activity indoors and outdoors.

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Science words

Anemometer - A device that measures speed

Barometer - A device for measuring air pressure

Buoyancy - The upward push of a liquid on an object placed in it.

Classify - To place materials that share properties together in groups.

Cold front - A boundary where cold air moves in under a mass of warm air.

Table of measurements

SI (International System) of units

1. Temperature

water freezes at 0 degrees Celsius and boils at 100 degrees Celsius

2. Length and distance

1,000 metres = 1 kilometre

100 centimetres = 1 metre

10 millimetres = 1 centimetre

3. Volume

1000 millilitres = 1 litre

4. Mass

100 grams = 1 kilogram

Compiled by Janani Amarasekara