Questions: Mass and Weight: What's the Difference?

Question 1

An astronaut has a mass of 70 kilograms on Earth. What is the astronaut's mass on the Moon?

• A. About 12 kilograms — the Moon has less gravity
• B. 70 kilograms — mass does not change based on location
• C. 0 kilograms — there is no gravity on the Moon
• D. 140 kilograms — the Moon doubles your mass

Answer: (B)

Mass is the amount of matter in an object, and it stays the same no matter where you are. The astronaut is still made of the same amount of stuff on the Moon. Weight would change (the astronaut would feel lighter because the Moon's gravity is weaker), but mass does not.

Question 2

A bowling ball and a basketball are about the same size, so they have the same mass.

• T. True
• F. False

Answer: False

False. The bowling ball has much more mass than the basketball even though they are similar in size. The bowling ball is packed with dense, heavy material, while the basketball is mostly filled with air. Mass depends on how much matter is inside, not on how big the object looks.

Question 3

What is the difference between mass and weight?

Model answer: Mass is the amount of matter in an object and stays the same everywhere. Weight is the force of gravity pulling on that mass and changes depending on the strength of gravity (for example, you weigh less on the Moon than on Earth, but your mass stays the same).

Mass is an intrinsic property of matter — it belongs to the object itself. Weight is a force that depends on the environment. On Earth, we often use the words interchangeably in casual conversation, but in science they have precise, different meanings.