AIM OF THE EXPERIMENT: To find the position of the centre of gravity.MATERIALS: plasticine, two metal forks, a toothpick, a tall glass or a jar with a wide neck. METHOD: Roll a ball of plasticine about 4 cm across.
Stick a fork into the ball.
Stick the second fork into the ball at an angle of 45 degrees to the first fork.
Stick the toothpick into the ball between the forks.
Rest the end of the toothpick on the rim of the glass and move it towards the centre of the glass until it balances.
NOTE: If you cannot get it to balance, reduce the angle between them.
RESULTS: At a certain position of the toothpick the forks balance.
WHY? Because the forks are set at an angle to each other, their weight is as it were concentrated at a particular point of the stick between them. This point is called the centre of gravity.