First Semester Science Review – Part 3 DENSITY

1. EXPLAIN HOW TO CALCULATE THE DENSITY OF REGULAR AND IRREGULAR OBJECTS.

D =

Density formula and Units Density = mass OR mass ÷ volume volume Units for density : g or gor Kg cm 3 ml L ALWAYS REMEMBER UNITS!

Density of objects Regular Shaped = Box/Cube ◦ Find mass on a triple beam balance ◦ Find volume using L x W x H ◦ Mass/Volume Irregular Shaped = Weird shaped ◦ Find mass on triple beam balance ◦ Find volume using water displacement ◦ Mass/Volume

Which one is more dense? Which square is more dense? Why? Why? Same volume, more mass

Which one is more dense? Now which one is more dense? Why? Why? Same mass, less volume

Let’s try a density problem together Frank has a eraser. It has a mass of 9g and a volume of 3cm 3. What is its density? 9 g ÷ 3 cm 3 = _____ Answer: 3 g/cm 3 Frank also has an paper clip. It has a mass of 3g, and a volume of 1cm 3. What is its density? 3 g ÷ 1 cm 3 = ________ Answer: 3 g/cm 3

2. HOW CAN YOU KNOW THE DENSITY OF AN OBJECT COMPARED TO THE DENSITY OF WATER?

Density of water The density of water is 1g/ml (or one gram per milliliter) If a substance has less density than water it will float. If an object or substance has greater density than water it will sink. <1 g/ml Float ~1 g/ml Hover >1 g/ml sink

3. EXPLAIN WHY LIQUIDS WITH DIFFERENT DENSITIES FORM LAYERS.

Liquid Layers If you pour together liquids that don’t mix and have different densities, they will form liquid layers. The liquid with the highest density will be on the bottom. The liquid with the lowest density will be on the top.

Liquid Layers Imagine that the liquids on the right have the following densities: ◦ 15 g/cm 3 ◦ 10 g/cm 3 ◦ 3 g/cm 3 ◦ 9 g/cm 3 ◦ 7 g/cm 3 ◦ 12 g/cm 3 Match the colors to the correct densities. 3g/cm 3 7g/cm 3 9g/cm 3 10g/cm 3 12g/cm 3 15g/cm 3 LOW DENSITY HIGH DENSITY

4. WHAT IS NATURAL SORTING BASED ON? WHERE DO YOU FIND THE LARGER, DENSER MATERIALS, AND THE SMALLER, LESS DENSE MATERIALS?

Natural Sorting Natural sorting is when particles are arranged with dense, larger objects on bottom and small, less dense objects on top Water is an excellent natural sorter. Other sorters: wind, lava flows, gravity Sorting occurs based on density and the size of particles. If objects have the same particle size, but different density, denser will go to the bottom If objects have the same density, but different particle size, larger objects will go to the bottom. Sorted sequences almost always look layered

Which layer settled first? Is it most dense? Which layer has the least dense particles? Did it settle last? A B C D This section of rock was deposited by water. Remember… water sorts by density and size.

5. HOW ARE THE LAYERS OF THE EARTH RELATED TO DENSITY?

Atmosphere (least dense) Hydrosphere (water) Crust Mantle Inner Core (most dense) Outer Core LAYERS OF THE EARTH 1.

You are given an unknown object. You find its mass to be 28 g and its volume to be 10 mL. Using the chart below, determine which layer of the Earth the object would belong to based on its density. Sample Earth density chart: