What does mass measure?

What does mass measure?

• A. Density per unit volume
• B. Weight in pounds
• C. The amount of matter in an object
• D. Volume of the object

Answer: (C)

Mass measures the amount of matter in an object. It’s a quantity of “stuff” that stays the same regardless of location, because gravity can change the weight but not how much material there is. This is different from weight, which is the gravitational force on that mass and can vary with location; and from volume, which is the space the object occupies. It’s also not density per unit volume—that would mix mass and how tightly packed the material is. In HVAC work, you often deal with mass when thinking about refrigerant charge or air mass flow, and you can relate it to volume flow using density.

Mass measures the amount of matter in an object. It’s a quantity of “stuff” that stays the same regardless of location, because gravity can change the weight but not how much material there is. This is different from weight, which is the gravitational force on that mass and can vary with location; and from volume, which is the space the object occupies. It’s also not density per unit volume—that would mix mass and how tightly packed the material is. In HVAC work, you often deal with mass when thinking about refrigerant charge or air mass flow, and you can relate it to volume flow using density.