Density

Density compares the mass of an object to its volume What is density? Density compares the mass of an object to its volume

Which one is more dense? Demonstration: People in a square How about this: Which square is more dense? How do you know?

Which one is more dense? Now which one is more dense? Why?

What is density? Density = mass OR. volume Units for density: g cm3 Why are these the units for density? ALWAYS REMEMBER UNITS!

a formula To find volume, use… water displacement 1. V = p r2 h V = l w h 2. water displacement V = ? Vfinal Vinit Vobject = Vfinal – Vinit

Equation of a Straight Line y = mx + b Slope Y intercept

Slope of a Straight Line The Slope of a straight line shows how steep a straight line is. Calculate: Divide the change in height by the change in horizontal distance Slope = Change in Y Change in X

Examples: Mass (g) Slope = 3 g = 1 g 3mL mL density Volume (mL) Slope = density = 4 g = 2 g 2mL mL Mass (g) Volume (mL)

Solving problems in science using the GUESS strategy Given Unknown Equation Substitute Solve

Let’s try a density problem together Frank has a paper clip. It has a mass of 9g and a volume of 3cm3. What is its density? Frank also has an eraser. It has a density of 3g/cm3, and a volume of 2cm3. What is its mass? G U E S m= 9 g V= 3 cm3 D D= M V D = 9g 3 cm3 3 g cm3 G U E S d= 3 g/cm3 V= 2 cm3 M D= M V 3 = m 2 6 g

Liquid Layers – Try with your neighbor Which liquid has the highest density? Which liquid has the lowest density? Which liquid has the middle density?

Liquid Layers Check out this picture. Which layer has the highest density? How do you know? Which layer has the lowest density? Imagine that the liquids on the right have the following densities: 15g/cm3 10g/cm3 3g/cm3 9g/cm3 7g/cm3 12g/cm3 Match the colors to the correct densities. 3g/cm3 7g/cm3 9g/cm3 10g/cm3 12g/cm3 15g/cm3