All of us have seen the balance measuring weights. The ancient Egyptians first invented it. We can still see it in use with the fruit and vegetable sellers. It is also used by jewellers and in the laboratories.
Let us make a balance for measuring weights and see how it works.
Things Required :
a sheet of cardboard of 6 x 2.5 inches, scissors, a screw, a thin stiff wire, drinking straw, two pieces of mount board 5 x 2.5 cm, a pen, a piece of plywood 8 x1.5 inches thick, cotton, a ruler, pliers, modelling clay, cotton and double sided adhesive tape.
Take a sheet of mount board and draw a scale with marks 0.5 inch apart. Then attach the scale to one end of the plywood with the help of the tape. Stick a small of piece cardboard on both sides of the other end. This will act as a support. Taking the straw, make a notch of about one inch at one end. Insert a two inches piece of wire through the straw. Next, push the screw into the straw and fix it with clay.
Place the wire at the other end of the straw, on the two small supports. One end of the straw must be pointing at the top of the scale. Place the cotton on the notch in the straw.
It will be observed that the pointer's position changes. This change shows the weight of the cotton.