Mass

Mass tells us how much stuff is in something. Everything you can touch has mass, from a tiny ant to a huge mountain. We measure mass in grams and kilograms. Mass does not change when you move an object. It stays the same on Earth, on the Moon, or in space.

Measuring Mass

Scientists use a tool called a balance to measure mass. A balance compares an object to known weights. If both sides match, you know the mass. Small things are measured in grams. Bigger things are measured in kilograms. One kilogram is the same as 1,000 grams.

Mass Is Not Weight

People often mix up mass and weight. Mass is the amount of matter in a thing. Weight is how hard gravity pulls on it. On the Moon, your weight would be less because the Moon has less gravity. But your mass would still be the same. You would still have the same amount of stuff inside you.

Fun Facts

• A paper clip has a mass of about one gram.
• The mass of the Earth is about 6 billion trillion tons.
• Even air has mass, though it is very small.

Did You Know?

The metric system uses a special object in France called the kilogram to help measure mass around the world.