Question

What is the mass in kg of a person who weighs 185 pounds?

Answer 1

Hint: The conversion relation between pounds and kg is such that 1 kg is around 2.2 pounds. The reverse of that relation yields the result that around 0.454 kgs are present in 1 pound. Pound is also denoted by lbs as it was derived from roman word Libra.

Complete step-by-step answer:
Kilograms or kg is the unit of measuring mass in a standard, internationally accepted system of units also called the S.I. units. Pounds is more of an imperial unit and is widely used in a few countries like the United States of America.
We can find the mass in the following two ways then:
1. ${\text{mass in kg = }}\dfrac{{185{\text{ pounds}}}}{{2.2}} = 84.09$
2. ${\text{mass in kg = }}185{\text{ pounds}} \times 0.454 = 83.99$
Therefore, the mass of the person weighing 185 pounds is around 84 kg.

Additional Information: Measurement of weights was done previously by keeping a standard reference weight for a kilogram which was internationally recognized and so was the case for other S.I. units too. There was a physical reference weight, cylinder of platinum-iridium which was used as reference. In 2019, precise measurement of Planck's constant helped in eliminating the previous definition of kilogram. A kilogram is now given in terms of h, c and atomic transition frequency. These constants are in general more fundamental and are measured precisely. This helps in eliminating room for errors and helps in producing repetitively precise results.

Note: Here mass has to be written in kg. A confusion might arise about weight and mass here as the question asks for 'mass' and tells how much it weighs. Weight is a measure of how much force that body exerts. Mass is a measure of physical composition of that body.