ShareForce, Energy, & Motion - Weight and Mass
Sometimes people use the words weight and mass to mean the same thing. This, however, is not accurate. Weight is related to mass, but it is not the same. Scientists measure weight using a unit called the newton (N). Usually we refer to weight in pounds and ounces. Weight is a measure of how gravity affects the mass of an object.
Mass is the amount of matter in an object and does not change with location. Scientists measure mass using a unit called the gram (g). If an object is moved to a location of greater gravitational force, such as Jupiter, its weight will increase, but mass still remains the same. The only way to change the mass of an object is to take away part of the object or add to it.
An object with a mass of one kilogram (kg) has the same mass on another planet, like Jupiter. However, because Jupiter is larger, the weight of the object would be different. In other words, the two planets would exert a different gravitational force on the same object.
Look closely at the images below. The same scientist is seen in each image. The comparisons between weight and mass here are based on data from Earth and its moon.
Analysis:
- What is the mass of the scientist?
- Which of these two objects is exerting the greater gravitational force - the Earth or its moon?
- Which is a more accurate measurement - mass or weight?
