1. Mass, Volume and Density

2. Metric System  Developed by the French in the late 1700’s.  Based on powers of ten, so it is very easy to use.  Used by almost every country in the world, with the notable exception of the USA.  Especially used by scientists.  Abbreviated SI, which is French for Systeme International.

3. Mass  Mass is the amount of matter that makes up an object.  A golf ball and a ping pong ball are the same size, but the golf ball has a lot more matter in it. So the golf ball will have more mass.  The SI unit for mass is the gram.  A paper clip has a mass of about one gram.  The mass of an object will not change unless we add or subtract matter from it.

4. Measuring Mass  We will use a triple beam balance and a digital top-loading scale to measure mass.

5. Earth 1 gravity Moon 1/6 th gravity Jupiter 2.5 gravities Jill’s mass30kg Jill’s weight300N50N750N Notice that Jill’s mass never changes. Jill is 30kg of little girl no matter where she goes! Weight and Mass

6. Volume  Volume is the amount of space an object consumes.  The base unit for volume is the liter.  There are two methods for finding volume.

7. Volume of Regular Objects  We can find the volume of box shapes with the formula Volume = length x width x height.  In this case the units would be cubic centimeters (cm 3 ).  So a box 2 cm x 3 cm x 5cm would have a volume of 30 cm 3 2 cm 3 cm 5 cm

8. Volume of Irregular Objects  We measure volume of irregular objects with a graduated cylinder.  This method is called water displacement  Liquids form a curved surface in graduated cylinders.  Take your reading at the low point of the curve or meniscus

9. Water Displacement  Pour 7 ml of water in a graduated cylinder. If a rock causes the level to rise to 9 ml, the rock must have a volume of 2 ml.

10. Liquid Volume  1 cm 3 = 1 ml  1 cm 3 of water = 1 ml of water = 1 gram of water

11. Water Mass and Volume  50 ml (50cm 3) of water would have a mass of 50 grams  1 Liter of water would have a mass of _______?  1 L = 1000 mL so its mass would be 1000 grams or a kilogram.

12. Density  Density is the amount of matter (mass) compared to the amount of space (volume) the object occupies.

13. Density  Density = mass/volume  Remember, all fractions are division problems.  Since the unit for mass is grams, and the unit for volume is ml or cm 3, then the unit for density is g/ml, or g/ cm 3

14. Density Formula Wheel  Formula wheels make it easy to solve density problems.  Cover the property you are trying to find, and do what is left over.  To find density, cover the word density. You have mass over volume remaining. So divide mass by volume to find density! Mass DensityVolume

15. Understanding Density  In the following illustration, each square will represent 1 cm3.  Each g will represent 1 gram.  Mass = 24g  Volume = 8 cm3  Density = ?g/cm3 g