Thanks to Newton, gravity is a measurable force. Not coincidentally, the international standard unit of force is called a Newton (N). On Earth’s surface, roughly 0.98N equals the downward force of gravity on 100 grams of mass.

Likewise, one kilogram of mass exerts a downward force of 9.8N. To calculate the force of gravity, physicists use the formula f = ma (force = mass x acceleration).

Since the acceleration of gravity is 9.8m/s2 on Earth – ie little g – we can easily calculate the Newton force of any mass. The average person’s mass is 70 kilograms, which multiplied by 9.8 gives you 686N – the force by which gravity keeps us all securely grounded.