What is weight? The weight of a body is the force which pulls the body towards the earth. It is the force which must be overcome when lifting anything. Greater force is needed to lift a heavy body than to lift a light body. The mass of a body depends on how much material is present in that body. The more material present, the heavier the body. The nature of the material determines how much a given volume of it weighs.
The weight of a body will vary between the Earth’s surface and 100 miles into space – its mass will remain constant.
Units of mass. To measure anything, we need standard units of measurement. We can then find how many standard units (of mass, length, etc) are equivalent to the material we are measuring. Metric units are now the approved standard units. Small quantities are measured in grams, but larger quantities are measured in kilograms. (“kilo” simply means 1,000). The kilogram, is equal to 1,000 grams, and the metric ton is equal to 1,000 kilograms.