What is Mass versus weight?
[[File:Mass versus weight in earth and mars.svg|300px|right|thumb|Mass of the object is same on [[Earth]] and [[Mars]], but it has a bigger weight on Earth than Mars because gravity of two planets are different.]] In the [[Physics|physical sciences]], '''mass and weight''' are different. The [[mass]] of an object is a [[measure]] of the amount of [[matter]] in the object. [[Weight]] is a measure of the [[Force (physics)|force]] on the object caused by a [[gravitational field]]. In other words, weight is how hard gravity pulls on an object. This means the mass of an object will remain at wherever it is on the earth's surface, but if it is moved from the [[equator]] to the [[North Pole]], its weight will grow by 0.5% because of the increase in the earth's gravitational field. [[File:Little girl on swing.jpg|thumb|right|260px|The chains on the swing hold all the child's weight. If someone were to stand behind her at the bottom of the swing and try to stop her, they would be acting against her [[inertia]], which comes from mass, not weight.]] Mass is measured in [[kilogram]]s or [[Pound (mass)|pounds]]. A one-[[litre|liter]] [[volume]] of water has a mass of one kilogram. Weight is measured in [[Newton (unit)|newtons]], the standard unit for force. A one-kilogram mass placed on a bench presses down on the bench with almost ten newtons of force. ==Overview== The weight of something is the value measured at the [[Earth]]'s surface. Unfortunately the common terms used to describe the weight of an object are units of mass such as kilograms or pounds. For almost all of human history weight has been measured on the surface of the Earth. Here, the weight is [[wikt:proportional|proportional]] to the mass. Objects which have the same mass have the same weight. An object with the twice the mass of another will also have twice the weight. As a consequence it is common practice to use the two words, mass and weight, as if they mean the same thing, and to use kilograms or pounds as the units for both mass and weight. Using th