Chem One Module # 1 -- Topic and Content -- Chapter 2 -- Types of Measurements -- page 3

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Weight and Mass:

What is the difference between Weight of an object and the Mass of the object?

Weight is the force of attraction of gravity on an object.

The Weight of an object on Earth depends on distance of the object from the center of the Earth. If we decrease the distance of the object from the center of the Earth, then the Weight of the object will increase. Thus a person would weigh more in Death Valley, California (which is the lowest land point in the United States) since the distance of the person from the center of the Earth has decreased. The same person will weigh less if they climb to the top of Mount Everest, since the person is farther away from the center of the Earth. Needless to say, that the reason that Astronauts experience weightlessness is because they are quite a distance from the center of the Earth.

Mass on the other hand is the measure of the amount of matter or material that an object possesses or is made of.

Mass is a comparison measurement. To determine the mass of an object, a comparison of the object to a known mass is made on an instrument called a balance. If the unknown object and the known amount of mass "balance out", then they have equal amounts of matter or mass.

The force of attraction of gravity on the two objects that are being compared has no effect on the measurements of mass.

In the illustration below the force of the attraction of gravity (represented by the hypotenuse of the right triangles) on each of the objects can be shown mathematically (A reason to study Trigonometry) to be the same. Therefore what is measured is not the force of attraction of gravity (or weight) but the amount of matter (or mass) that composes the objects.

Thus mass is a constant property that is independent of the location of object on earth (or in space for that matter)