Aim: How can we determine the density of an object? Note Pack #4 Aim: How can we determine the density of an object? *Knock Nevis (worlds largest ship) Do Now: How does a ship weighing over 1,245,000,000 pounds float? *Write down your reasons.

What is density? Density is a comparison of how much matter (atoms) there is in a certain amount of space. You cannot look at something and determine how dense it is. You cannot change the density of something if you break it apart into smaller pieces. (The density remains the same.)

What do you need to determine the density of an object? To determine what the density of an object is, you need to know 2 things: The mass of the object and what volume the object occupies. Mass (g) Is the amount of matter in an object/substance. To get the mass of an object you must measure it using a scale. The mass of an object is not the same as weight (weight varies depending on gravity) A 150 pound person on Earth weights 25 pound on the Moon and 355 pounds on Jupiter, yet that person’s mass did not change. Volume (ml or cm3) Is the amount of space an object/substance takes up. To get the volume of an object you must measure it using a ruler or a glass filled with water.

Volume of the red cylinder is 2 cm3 To Measure the Volume of an Object 7 – 6 – 5 – 4 – 3 – 2 – 1 – Volume of the red cylinder is 2 cm3

Density is the measure of the “compactness” of a material More than just the “heaviness” of a substance, density includes how close atoms are to each other in a given space!! All substances have density including liquids, solids, and gases. A substances density can change as that substance changes from one phase of matter to another. Example: Water to Ice - (Ice is less dense than water) Bread slice and compacted bread in large flask of water 5

“Compactness” Hot air balloon - Describe how a hot air balloon works. Defend your argument. 6

DENSITY! Which has more mass 100g of feathers or 100g of bricks? Which of these take up more space? Which of these is more dense?

The Formula for Density ON page 1 of your Earth Science Reference Tables. Middle-left Abbreviated M=mass V=volume

Find the Density of… An object with a mass of 35.67g and a volume of 12.33 cm3. The formula is D = M/V D = 35.67 / 12.33 D=2.891g/cm3

The Formula for Volume ON the front of your Earth Science Reference Tables. M=mass V=volume

Find the volume of… An object with a density of 12.77 g/cm3 and a mass of 134.22g V = M / D V = 134.22 / 12.77 V = 10.51 cm3

The Formula for Mass ON the front of your Earth Science Reference Tables. M=mass V=volume

Find the Mass of… An object with a density of 12.77 g/cm3 and a volume of 11.29 M = V x D M = 11.29 x 12.77 M = 144.1733 g

What makes objects float on water? Density of water is 1 g/cm. Anything with a density more than 1 will sink. Anything with a density less than 1 will float.

What makes objects float on top of another object? Objects tend to separate and layer themselves based on density. Objects that are less dense than others tend to “float” on top of more denser objects. Objects that are more dense than others tend to “sink” below less dense objects.

"Mountains over deserts and valleys" THE TRICK M D V

Cover up the one you want to solve for! M D V

Let’s solve for VOLUME. “M over D” is remaining so we divide! M D V

Let’s solve for Density. “M over V” is remaining so we divide! M D V

Let’s solve for Mass. M D V x “D next to V” is remaining so we multiply! M D V x

What can affect the density of an object? The density of an object does not always stay the same. Temperature can affect the substance shape. Ex. Lid on a jar. If the volume of the substance change; so does its density. As substances change in phases (solid, liquid and gas) the density also changes. Pressure also affects density. More Pressure = More Density

- 4 - 3 - 2 - 1 1 1 1 1 1 1 1 1 1 1 10 mass / 2 volume = 5 density

Does the density change if you cut an object into smaller piece? 6 – 5 – 4 – 3 – 2 – 1 – 0 – 0 1 2 3 4 Cutting an object into smaller pieces will not change the density of the object. Although the volume is getting smaller, so is the mass. The volume and mass are in direct relationship with each other. Volume Mass D = M/V D= 4/6 D = 2/3 D = M/V D= 2/3 D = 2/3