Science Projects Index

Making Work Easy With Pulleys

On a big wooden beam fix one hook. Now fix a cotton reel as a sort of pulley on this hook. Loop a length of rope over the cotton reel and then tie a pail of sand on to one end of the rope. Now pull the rope. You will find it easier to lift the pail of sand. After this, you fix one more hook on the beam and tie one end of the rope to it. At the same time fix the pail of sand on to another cotton reel. Arrange the loop as shown and pull the rope to raise the pail. You will find that pulling the pail is easier than earlier.

Weight and How It Changes

Take a half kilo weight and hang it on a spring balance using a string tied round the weight. The spring balance would show a reading of half a kilo. Now immerse the weight in water and in that position read the reading on the spring balance. It would be seen to be less than earlier. This is because of the buoyancy or the upward thrust of the water.