Mass

Mass is a measure of the amount of matter in an object. All matter has mass, and the more matter present, the greater the mass. The SI unit of mass is the kilogram, but in the science laboratory mass is often measured in smaller units such as grams or milligrams.

Mass and Weight

The weight of an object is very different from the mass. The weight is the measure of the force of gravity on its mass. Weight is defined as the mass times the acceleration due to gravity (weight = mass x gravity).

Since the weight is a measure of force, it has a different unit of measurement. The SI unit for weight is the Newton (N). One Newton is defined as the amount of force required to cause one kilogram to accelerate one meter per second every second.

Mass is a quantity that does not vary with location, but weight will change when acceleration due to gravity changes. For example, since the Earth pulls on matter with a greater force than the moon pulls on matter, the weight of the same object will be different.