Hobbies And Interests
Mass Defined
Mass is defined as the amount of matter an object contains. In other words, mass is a measure of how much stuff has been used to construct an object. For example, a lead bar contains far more atoms than an aluminum bar of the same size. Thus, the lead bar has more mass. Mass is one of the three fundamental quantities in science. All other mechanical properties are defined using these fundamental quantities ̵1; mass, length and time.
Weight Defined
Weight is defined as the vertical force exerted by a mass as the result of gravity. Stated differently, weight is a measure of the pull of gravity on an object. It is not a fundamental quantity; rather, it is a mechanical property. As such, it is defined by using a fundamental quantity ̵1; mass. Weight is equal to an object̵7;s mass times the acceleration of gravity in a given location. Weight is a force, not a quantity such as mass.
Mass Is Constant
Because the amount of matter an object is made from does not change, an object̵7;s mass is always constant. This is true no matter where the object may be located. For example, a given hippopotamus has the same amount of mass on land as it does in water. Likewise, you would have the same amount of mass on the moon as you do on Earth. This does not mean that mass cannot be added or lost, simply that mass is not altered merely by moving an object̵7;s location.
Weight Is Variable
Weight is a measure of gravitational affect and, therefore, will necessarily vary as the force of gravity on an object changes. For example, that same hippopotamus will weigh more on land than in water. This is because the buoyant force of water will reduce the force of gravity acting on the animal. Likewise, you would weigh less on the moon than on Earth, because the force of gravity acting on your mass would be less. In fact, you would weigh about one-sixth your weight on the moon when compared to your weight on Earth.