Triple Beam Balance and Density

Unit 6 Day 3 - Density

Physical Science

Density

You know, just a general measure of how much "stuff" is in there, very technical...

Open Ended

Not knowing technically what density is yet, what does your gut tell you? Which is "more dense", the balloon of air or the bowling ball? What makes you think that?

Particle Diagrams and Density

• We can imagine the "stuff" as particles and recognize that both the amount of particles (mass) and the space they occupy determine the density

• Let's compare and discuss A and B...

• Now let's compare and discuss A and C...

Multiple Choice

Which diagram shows the MOST dense object?

• left

• center

• right

Multiple Choice

Which diagram shows the LEAST dense object?

• left

• center

• right

Multiple Choice

Rank the objects from MOST dense to LEAST dense.

• left, center, right

• right, center, left

• left, right, center

• right, left, center

• center, left, right

Density Defined

Density is how tightly or loosely packed the particles of matter are.

And how much those particles weigh

Reorder

Create the formula for density by re-ordering the blocks below.

• Density

• $$=$$  

•  Mass

• $$\div$$  

• Volume

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

What is mass?

Mass is just a measurement of how much matter an object is made of.

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In it's simplest definition, mass is the amount of stuff anything is made out of.

​

You're made of matter, so you have a mass! So does the chair you're sitting on and the air you breathe.​

What is volume?

Volume is a measurement of how much space an object takes up.

​

Really simply, volume is a measure of the size of anything. Objects with larger volume take up more space!​

What is density?

Density is a measurement of how much matter is inside of an object of a certain size (mass per volume).

​

If an object has a high density, it means that there's a lot of stuff packed together inside of it.

Match

Match the variable to its correct definition.

• a measurement of how much matter an object is made of.

• a measurement of how much space an object takes up.

• a measurement of how much matter is inside of an object of a certain size

mass

volume

density

• mass

• volume

• density

In other words, this is how we know that gold is gold and water is water. Each substance or material has a unique amount of "stuff" (matter) that makes it.

​

The density of any material is unique to that material

​

One tiny piece of gold has the same density as a giant bar of gold.

​

Confused? Let's use the formula for density to figure it out.​

No matter the amount of a material we have, its density is always the same.

​

​Density of Gold

Let's say we have one big piece of gold​ that has a volume of 10 cubic cm.

That's about the size of a dice cube. We weigh the gold dice and find its mass is 193g.

​

Let's say we have another small piece of gold that's about the size of an apple seed at 1 cubic cm. We weigh the gold seed and find its​ mass is 19.3g.

​Volume: 10cm³

Mass: 193g​

​Volume: 1cm³

Mass: 19.3g​

The density of the gold cube is:

​

​

The density of the gold seed is: ​

​

​Density of Gold

​Volume: 10cm³

Mass: 193g​

Density: 19.3g/cm³​

​Volume: 1cm³

Mass: 19.3g

Density: 19.3g/cm³​

​Both pieces of gold have a density of 19.3g/cm³

​= 19.3g/cm³

​= 19.3g/cm³

Match

Match the statements.

• Two similar sized pieces of the same material...

• Two similar sized pieces of different materials...

• Three different sized pieces of different materials...

Have the same densities.

Have two different densities.

Have three different densities.

• Have the same densities.

• Have two different densities.

• Have three different densities.

Multiple Choice

A pebble has a mass of 35 grams and a volume of 14 cubic centimeters. What is its density?

• 0.4 g/cm³

• 2.5 g/cm³

• 490 g/cm³

• 4.0 g/cm³

Multiple Choice

What is the density of a 40-gram object whose volume is 20 ml?

• 2 g

• 2 ml/g

• 2 g/ml

• 2 ml/g

Multiple Choice

If the cube below were cut into four smaller cubes, the density of one of the small cubes, compared to that of the original cube, would be

• one-fourth as great

• the same

• four times as great

• one-sixteenth as great

Multiple Choice

A student is studying a mineral in Earth Science class. They determine one characteristic of the mineral and record this number and unit in their notebook: 12g/cm³

What characteristic is represented by the units of g/cm³ ?

• Density

• Mass

• Volume

• Weight

Multiple Choice

A student correctly determined the density of two rocks. If the volumes of the two rocks are equal, the rock with the greater density has a

• rounder shape

• smoother surface

• greater mass

• smaller size

Measuring mass

• with a triple beam balance

• with a digital scale

Volume

Volume is defined as the amount of space an object takes up. Because matter takes so many different forms, volume can be measured many different ways.

Cube or Rectangle

To measure the volume of a cubed or rectangular shaped solid all you need is a ruler. Measure the length, width, and height of the object and then multiple the three numbers together.

Volume = length x width x height

Practice

Now you try calculating the volume of the cube on the right.

Open Ended

How do you measure liquid volume using a Graduated Cylinder?

Practice

Another thing to consider when finding the volume of a liquid is the markings on the graduated cylinder. Look at graduated cylinder in the practice problem. The two lines that are marked are 6 mL and 8 mL. That means that each marking between 6 mL and 8 mL is equal to 0.2 mL. Graduated cylinders are often marked differently, so don't forget to check!

Multiple Choice

What is the volume of the water in this photo?

• 6mL

• 6.4mL

• 7mL

• 6.6mL

Water Displacement

Now that you can find the volume of a liquid, you can find the volume of an irregular solid. How would you find the volume of a rock? It wouldn't be very easy to use a ruler because rocks can have so many different shapes. Instead, you can use a method called water displacement.

Procedures to find the volume of an irregularly shaped object using water displacement:

• Start with a known amount of water and record the volume.

• Place the object in the water and record the new volume of the water.

• Subtract the first volume from the second volume and that will give you the volume of the object.

Take a look at the picture of the graduated cylinders on the left.

The cylinder starts with 200 cm³ of water.

When the rock is dropped in, the volume goes to approximately 270 cm³. (1mL=1cm3)

If you subtract 200 cm3 from 270 cm³ you get 70 cm³.

So the volume of the rock is 70 cm³.

Multiple Choice

What is the volume of the fish?

• 40mL

• 6mL

• 38mL

• 8mL

​Density Lab