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Home Concept Builders Newton's Laws Mass and Weight Help Help 3

Mass and Weight - Questions 3 Help

Mass and weight are entirely different concepts that refer to two different measureable quantities. A thorough grounding in these concepts is essential to success in Physics.

There are three similar versions of this question. Here is one of those versions:
 

Version 1:
Consider the following three statements. Two are true and one is false. Identify the false statement.
 
The mass of an object on Earth is identical to the mass of the same object on the moon.

The weight of an object is equal to its mass multiplied by the force of gravity.

The weight of an object is equal to the force with which gravity pulls upon the object.

The concepts of mass and weight are often confused. The mass of an object, most often expressed in kilograms (kg), refers to the amount of stuff present in the object. More stuff (atoms) and more massive stuff (more massive elements) means the object possesses more mass. This mass value is not location dependent. A 2-kg textbook on the Earth would still possess a mass of 2 kg when it is brought to the moon.

The weight of an object is quite different. Weight refers to the force with which gravity pulls downward upon the stuff in the object. Weight is the gravitational force of attraction to the Earth (or to whatever massive body the object is on). Because weight is a force, it's standard unit is the Newton (N). And because it is a force of gravity, its value is dependent upon the gravitational environment where it is located. As such, the weight of an object varies with location. A 2-kg textbook would weigh approximately 20 N on Earth; but when brought to the moon, it's weight would be less than 4 N. The weight of an object can be calculated by multiplying the mass of an object by "g". This g value is known as the gravitational field strength (often referred to as the acceleration of gravity).

Try this link to The Physics Classroom Tutorial for more help with mass and weight:

Types of Forces (Mass and Weight section)

Concept Builder Teacher Notes Directions