I have learnt that if two objects attract each other with a gravitational force of 16 units, and the distance between the two objects is then doubled, to get the new force of attraction which would, naturally, be less, you must square the doubling which is 4, then inverse it which is 1/4, so the new force of attraction is a quarter of 16 which is 4.
How Newton worked that one out from an apple bashing him on the head as he lay under a tree is beyond me. I once had a large tom cat land on my head as I lay under a tree and all I discovered was that it hurt. If I'd been Isaac Newton though I'd have have probably calculated the moggy's weight from the gravitational force that it hit me. Instead, I experimented with centrifugal force, spinning it round by its tail then releasing it at high speed back to our neighbour's garden where it belonged, except that it overshot the mark by several fences.
