Density

DENSITY is a physical property of matter. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume.

For example:

Take three cups that are the same size. If you fill one cup with water, one with sand, and one with lead. Would they all weigh the same? No, of course not. A cup of sand weighs more than a cup of water. Sand is denser than water. Lead is denser than sand, so a cup of lead weighs more than a cup of sand.

Density also explains why things float. If a cubic centimetre of wood weighs less than a cubic centimetre of water, the wood will float. The wood is less dense than the water. If a cubic centimetre of lead weighs more than a cubic centimetre of water, then the lead will sink. Lead is more dense than water.

Use this idea to make several layers of liquid that will let you compare the density of different objects.

You will need:

a tall, clear glass or jar- water (coloured with food colouring)

vegetable oil- golden syrup

a variety of small objects such as: cork, rubber, plastic, corn flakes, ice, a piece of apple, etc.

a spoon

Pour about one and a half inches of golden syrup into the glass. Place the spoon just at the top of the layer of syrup and gently pour in another inch or so of water. The water should form a layer on top of the golden syrup, and by pouring it into the spoon, you keep from mixing the two layers. Keeping the spoon in place, add an inch or so of cooking oil to form the top layer. When you finish, place the glass on the table and look at it from the side. You should be able to easily see the different layers of liquid.

The golden syrup is the densest, so it is on the bottom. Next is the water, then the oil, which is the least dense. Now, drop your variety of objects in individually Notice which layer each floats on. That tells you their relative density.