What is the difference between mass and weight?

• A. Mass is the gravity on an object; weight is the amount of matter
• B. Mass and weight are the same
• C. Mass is the amount of matter; weight is the force of gravity on that mass
• D. Mass is a measure of temperature

Answer: (C)

Mass is the amount of matter in an object. Weight is the force of gravity pulling on that mass. Because gravity changes with location, an object’s weight changes from place to place, but its mass stays the same. The weight can be found with the idea that weight equals mass times gravity (W = m × g). On Earth, gravity is about 9.8 m/s^2, so a 5-kilogram mass weighs roughly 49 newtons; on the Moon, where gravity is weaker, the same 5-kilogram mass weighs about 8 newtons. A balance scale measures mass by comparing amounts of matter, while a spring scale measures weight by responding to gravitational force. Mass is measured in kilograms; weight is measured in newtons. The other options mix up what mass and weight mean or bring in temperature, which isn’t related to this concept.