Body Mass Index is calculated by dividing your weight in kilograms by the square of your height in metres.

BBC: Head-to-head: Fat tax

They measured height, weight and body mass index - calculated by dividing weight in kilograms by the square of your height in metres.

BBC: Curvier women 'will live longer'

The mass can thus be calculated.

ECONOMIST: The 2002 Nobel prizes: Windows on the world | The

By digitising the outline of each jumping gibbon frame by frame, they revealed how its centre of mass moved, and they calculated the forces needed to propel 6kg (a stone) of hairy ape through the air.

BBC: Gibbons' extraordinary jumps 'down to technique'

By combining data from the two steps an equation linking mechanical power (dependent on mass) to electrical power (calculated by multiplying voltage by current) can be derived.

ECONOMIST: Weighing a kilogram

Studying the ripples allows the mass of the deflecting objects to be calculated.

ECONOMIST: Cosmology

Senior State Department officials said Friday's move was part of a "carefully calculated series of steps" the United States decided to take in response to Libya's cooperation on weapons of mass destruction.

CNN: U.S. lifts most sanctions against Libya