Density OR, WHY SOME THINGS FLOAT WHILE OTHERS SINK.

What is Density? Density how heavy something is for its size. Density is mass divided by volume OR D=m/v D = density, m = mass, v = volume

Another way to look at it. Often called “mass per unit volume” –Mass amount of matter in an object –Per means divided by –Unit volume a measure of how much space it takes up. So when you hear mass per unit volume, you should think… D=m/v.

What are units of Density? Mass units would include –Grams for very small objects –Kilograms for large ones Volume units include –Cubic centimeters (cm 3 ) –Cubic meters (m 3 ) –Milliliters for small liquid –Liters for larger liquid

How to State Density Units You have grams for mass You have cubic centimeters for volume Neither will cancel so… – units are g/cm 3

What is Density?

A few words about the mass/volume relationship of liquids and solids When you have a sample of any liquid or solid –If you decrease the mass, you will also decrease the volume. –If you increase the volume, you will also increase the mass. –We must assume the DENSITY remains constant

A few words about the mass/volume relationship of liquids and solids –So when the mass or volume of a sample is changed the density DOES change. –If the sample is melted the density will decrease slightly. –When compressing/freezing the object the density will increase slightly.