Two curriculum-relevant/open dayphysics experiments concerning gravity

Gravity is an intangible abstract force when considered theoretically and yet we areaffected by it constantly. The apparently ‘strong’ nature of gravity, which in the layperson’s mind causes him or her to stick to the Earth, is belied by the fact that it is the weakest of the fundamental forces. Demonstrations that allow pupils, parents or the public to conceptualise gravity afford delight and a sense of achievement and in this article we describe and review two easy-to-set-up demonstrations, one of which illustrates an interesting and counterintuitive property of gravity andthe other which allows a simple calculation for the value of the acceleration due to gravity.