# Mass

Mass is a measure of how much matter is contained within an object. It's SI unit is the kilogram.

The mass of an object can be found by pushing on it with a known force $F$ and dividing the size of that force by the resulting acceleration ($a$).[1]

$m = \frac {F}{a}$

Mass is different from weight (force) in that its value does not change if gravity changes. For example, on Earth, where the acceleration due to gravity is 9.8 m/s2, a person who has 60 kg of mass weighs 588 Newtons (132 lbs). On the moon, where the acceleration due to gravity is about 1/6 of what it is on Earth, that same 60 kg person weighs just 98 Newtons (~22 lbs).

## References

1. Sears, Zemansky, and Young, Fifth Edition University Physics. Addison-Wesley Publishing Company, 1979.

## Authors and Editors

James Jenden, Kailyn Stenhouse, Jason Donev