Science Projects Index
Density and Weight
Take ball, brick and an iron weight. Of the three, the ball is the biggest. Second comes the brick and the third is the iron weight. But the ball is the lightest, while the iron weight is the heaviest.
This shows that weight and size have no comparison, if it is of different substances. Now weight is connected to density.
If a thing is having a high density, then it will have a higher weight in comparison to a similar sized substance of lower density.
Take a cork and cut slits all round it. Then cut pieces of plastic and insert them into the slit. Through the middle of the cork insert a knitting needle. Bring it under a water tap. When the water starts flowing, the plastic sheets will turn causing the cork to rotate. This is how the electric turbines work under the dams to produce hydroelectric current.