Mass & Weight

1. Mass & Weight By Mr. Krall

2. What is matter? • Before we can learn about mass and weight, we need to know what matter is. • Matter is any atoms or parts of atoms: including solids, liquids, gases, and plasmas • Examples of matter – an atom, an electron, any liquid (like water,) oxygen gas, solid rock, or any kind of particles

3. What is mass? • Mass is a measurement of how much matter an object is made up of. • The more atoms (or parts of atoms) a substance or object is made of, the greater its mass. • The mass of an object is constant. It does not change.

4. Examples of Mass CRUSH SPLAT! Even if you pounded the urinal cake into mush, it would still have a mass of 50g, since it is still made of the same amount of matter. This urinal cake has 50g of mass. If you crushed a urinal cake down into half it’s size, the mass would still be 50g. The atoms would just be forced closer together. Two urinal cakes would have twice as many atoms for 100g of mass. Mass is the amount of matter (atoms or parts of atoms) an object is made up of. Mass doesn’t change. Floating in outer space, the urinal cake is made of the same amount of atoms. So its mass is still 50g. The change in gravity doesn’t change how many atoms the urinal cake is made up of.

5. What is weight? • Weight is the force of gravity pulling on an object. • The larger the pull of gravity on an object, the greater its weight becomes. • An object’s weight can change if the pull of gravity on that object changes.

6. Examples of Weight CRUSH SPLAT! gravity gravity gravity gravity Gravity pulls on the urinal cake’s particles. The force that it pulls on those particles is the weight of the urinal cake. The weight with Earth’s gravity is 50g. Even if you pounded the urinal cake into mush, it would still have a weight of 50g, since it is still the same particles and gravity will pull on them the same. If you crushed a urinal cake down into half it’s size, the weight would still be 50g. The atoms would just be forced closer together, but gravity would pull on them the same. Two urinal cakes would have twice as many atoms for gravity to pull on, so the weight doubles to 100g. Floating in outer space, the urinal cake is made of the same amount of atoms, but there is almost no gravity to pull on them. Therefore, the weight is 0g. No gravity force pulling on the urinal cake means it is weightless. Weight is the force of gravity’s pull on an object. Weight changes if the pull of gravity on an object changes. no gravity

7. The difference between: mass and weight • Weight depends on how strong the pull of gravity is on an object. • If you are on Earth, your weight is larger than on the Moon because Earth’s gravity is stronger than the Moon’s gravity. In space, where gravity is almost zero, you could be “weightless.” • Weight can change. My weight is almost zero in space, since gravity is hardly pulling on me at all!

8. The difference between: mass and weight (cont.) • Since mass tells how much matter an object is made of, that amount is the same wherever the object goes. • In outer space, you are made of the same amount of atoms as you were on Earth, so your mass is the same. A puzzle would be the same amount of pieces in space or on Earth. An object would be made of the same amount of atoms or atom pieces in space or on Earth.

9. MASS WEIGHT A measurement of the amount of atoms or parts of atoms an object or substance is made up of. A measurement of the force of gravity’s pull on an object. The mass of an object doesn’t change. The weight of an object can change if the force of gravity pulling on it changes. We measure mass with a triple beam balance. We measure weight with a spring scale. BOTH On Earth, the mass and weight of an object are the same number and units. (We take Earth’s gravity for granted.) Both the Metric and English systems can measure mass and weight of objects.