Why do scientist prefer to describe matter by its mass rather than its weight?

Mass and weight have different meanings, in scientific terms. Mass is a measure of the amount of matter contained in an object, solid lquid or gas. It is measured in kilograms, abbreviated kg, which is the SI unit for mass. It is unchanged no matter where the object is situated. Weight is measured in Newtons, abbreviated N. It is determined as the product of the mass of an object multiplied by the local acceleration due to gravity. As such it is in reality a measure of force, not amount of matter. If a 1kg mass is placed on the surface of the earth, it will have an average weight of 1*9.8 = 9.8N. This is because on average, the acceleration due to gravity on earth is 9.8m/s². If the same mass of 1kg is taken to the moon, it will still have a mass of 1kg, but its weight will be 1*1.633 = 1.633N. more