Newton was also very good at mathematics and he was able to describe this mysterious force as

where is known as ``BIG G'' or the gravitational constant. This is Newton's Law of Gravitation. Scientists have been able to measure this number to be

or rather, 6.67 hundred thousand millionths; pretty small!

Let us do a little experiment.

The mass of the Earth in kilograms is 6 with 24 zeroes after it. However, your average apple is only about 0.1 kg. If you lift the apple above your head to a height of 2 m say, then from Newton's Law we calculate the force of attraction (or force of gravity) to be 10 million million (10¹³) kg m s^-2.

Now, let us say that you weigh 60 kg (a wild guess!!). Your computer in front of you is probably about 30 kg. Your face is probably about half a metre (0.5m) from the computer screen. The force of attraction in this case is 4 ten millionths (0.0000004) kg m s^-2 .

But that is 100 million million million (10²⁰) times less than the force of gravity on the falling apple! No wonder you do not know anything about it!

But gravity plays a much greater role than simply helping apples drop out of the sky.