AIM OF THE EXPERIMENT: To show how the position of the centre of gravity can affect the motion of a body.MATERIALS: Two battens about a metre long: three books (at least 3 cm thick), adhesive tape, two identical funnels.
Place two books on the floor or on a table, one on top of the other, and at a distance a little less than the length of a batten place the third. Lay one batten as a bridge between the books. Place the second beside it so that a narrow angle is formed, with its vertex resting on the book that lies on its own. Join the funnels at their wide ends and fasten them with adhesive tape. Place the funnels between the battens, at the vertex of the angle they form. WHY? What is seen does not mean that the funnels disobey the law of gravitation. In fact, while the funnels themselves appear to move upwards, their centre of gravity (the point at which the weight of an object acts) moves downwards. Note that the centre of the joined funnels moves down as the funnels themselves travel along the battens, which rise. METHOD: RESULTS: The funnels roll up the battens.