MEASURING SMALL ITEMS

Small objects are measured in cm or mm.

How many mm are in 1 cm?

1 cm = _______ mm

When measuring small objects, measure to the nearest mm.

MEASURING METRIC LENGTH

USING A METRIC RULER

Start from 0! Read first to the nearest

cm. The numbers are cm

Read next to the nearest mm The small, numberless lines

are mm.

This red tape is 2.3 cm long

READING A METRIC RULER

LET’S PRACTICE!

Did you say 5.1 cm?

LET’S PRACTICE!

Did you say 7.1 cm?

VOLUME

VOLUME The amount of space an object takes up

CALCULATING VOLUME OF RECTANGULAR SHAPED SOLIDS

Calculate the volume using the formula:

Volume=L x W x H (length x width x height)

Width = depth Make sure you also multiply

the UNITS (cm x cm x cm = cm3 )

UNIT FOR VOLUME OF SOLIDS

objects with small volumes use cm3 (cubic centimeter)

1 cm3 is equal to the volume of a cube that measures 1cm on each side.

Objects with large volumes use m3 (cubic meters)

1 m3 is equal to the volume of a cube that measures 1m on each side.

HOW DO WE FIND THE VOLUME OF THIS?

1. Treat it like 2 rectangles.2. Find the L, W and H for BOTH

rectangles.3. Calculate volume for both

rectangles using L x W x H.4. ADD them together.

Rectangle 1: L = 80 mm, W = 10 mm,, H = 20 mm80 x 10 x 20 = 16 000 mm3

Rectangle 2: L = 20 mm, W = 10 mm, H = 40 mm20 x 10 x 40 = 8 000 mm3

Total Volume8 000 mm3 + 16 000 mm3 = 24 000 mm3

VIDEO INSTRUCTION

Optional Video – Calculating Volume

SIGNIFICANT FIGURES When calculating volume, your FINAL answer can

have no more decimals than your LEAST accurate measurement.

So, YOU MUST ROUND!

If you are measuring to the nearest millimeter, your answer should have ONLY 1 decimal point.

Example: 1.5 cm x 1.5 cm x 1.5 cm = 3.375 cm3 This answer is not possible. If we can only measure with a ruler to the mm place,

the answer CANNOT be beyond the mm place. Therefore, the correct answer would be 3.4 cm3

VOLUME Volume of Liquids

UNIT USED TO MEASURE LIQUID

base unit for liquid is Liter (L)

Small volumes are measured in milliliters (mL)

1000 mL = 1 L(which you should

know from practicing unit conversions!)

MEASURING VOLUME OF A LIQUID

Tool used to find liquid volume is Graduated cylinder.

Rules for Reading a Graduated Cylinders1. Place on flat surface.2. Read from the bottom

of the meniscus.3. Get to eye level with

the level of the liquid.

MENISCUS The curve in the top surface of liquid in the graduated cylinder

CALCULATING VALUE OF LINES ON GRADUATED CYLINDER

Find the difference between the labeled sections.

Divide by number of sections between them.

READING A MENISCUS - PRACTICE

Read the milliliter marking at the bottom of the curve

What is the value of each line on this cylinder?

What is the volume of liquid in this cylinder?

MORE PRACTICE!•Difference between the marked lines• 25-10 = 10 ml

•Number of sections between• 10

•10 / 10 = 1

•Value is 1 mL

HOW TO READ A GRADUATED CYLINDER - VIDEOWhat is the value of each line on these

cylinders?What is the volume of these cylinders?

TICKET OUT Liquid Volume

1. What is the name of the tool used the measure liquid volume?

2. What is the metric base unit for liquid volume?3. What is the base unit for smaller amounts of

liquid?4. What is the volume of the liquid in the cylinders

below?

A

B

C

VOLUME

Volume of Irregular Solids

FINDING THE VOLUME OF AN IRREGULAR SOLID OBJECT

Use the water displacement method

Steps1. Pour water to an even

value in a graduated cylinder.

2. Record amount as V1.

3. Carefully slide the object into the water. Record the volume as V2.

4. V2 - V1 = Volume of Object

HOW DOES THE WATER DISPLACEMENT METHOD WORK?

Video on Displacement

UNIT FOR IRREGULAR OBJECT?

Use cm3 for small irregular shaped objects.

How can something solid be measured in mL?

1 cm3 = 1 mL

LET’S PRACTICE

Find V1 Find V2 V2-V1= ?

MASS Mass is a measure of the amount of matter an object contains.

UNITS OF MASS

The basic unit of mass in the SI system is the kilogram (kg). Best for measuring the mass of

people, cars, or bicycles. For smaller units use grams (g)

Best for measuring mass of small objects like paperclips and cell phones

MEASURING MASS

To find the mass of an object use a triple beam balance. It compares the mass of the

object you are measuring to a known mass.

THE DIFFERENT PARTS OF THE TRIPLE-BEAM BALANCE.

PanRiders

BeamsPointer

USING A TRIPLE BEAM BALANCE

1. Set balance to 0.2. Place the object on the pan3. Shift the riders on the beams

until they balance the mass of the object

1. Start with the large rider (increments of 100)

2. Next, the medium sized rider (increments of 10)

3. Lastly, the small rider (increments of 0.1)

MASS VS. WEIGHT

Weight is a measure of the force of gravity acting on an object. Mass measures the amount of matter an object

contains, it remains constant. W = mass x gravity

Weight can CHANGE.

DENSITY

DENSITY The measure of how much mass is contained in a given volume

WHAT EXACTLY IS DENSITY?

Think about it as how heavy something is for it’s size.

Compare a basketball and a bowling ball. They are the same size but the bowling ball has more mass.

So which has more density?

CALCULATING DENSITY Density = Mass / Volume

( D = m/v )

UNIT FOR DENSITY

Because density is actually made up of two other measurements (mass and volume) an objects density is expressed as a combination of two units

Density of Solids g/cm³ (you say it as grams per

centimeter cubed)

Density of Liquids g/mL (you say it as grams per

milliliter)

DENSITY TRIANGLE

•If you know two of the three measurements in the density triangle, you can solve for the third.

•Cover the measurement you want to solve for and you are given the formula necessary for solving the problem.

•Example: Cover the D and you are left with m/v.

•Cover the M and you are left with D x V. To solve for mass use the formula M = D x V

•Cover the V and you are left with M/D. To solve for volume use the formula V = M/D

DENSITY TRIANGLE

•PRACTICE

•SOLVE for Volume •D = 10 g/mL•M = 100 g

•Solve for Mass•V = 25 mL•D = 100 g/mL

•Solve for Density•V = 10 cm3•M = 150 g

DENSITY “RULES”

Density is a characteristic property of a substance.

All samples of a specific substance will have the same density. It doesn’t matter how big or small the sample is.

Density can be used to identify what a substance is. It is very useful!

Example (find the density): 1 cm3 of gold has a mass of 19.3 g.

2 cm3 piece of gold has a mass of 38.6 g.

Density of common substances Ice- 0.9 g/cm3

Water- 1.0 g/mL Aluminum- 2.7 g/cm3

Gold- 19.3 g/cm3

FIGURE 6: APPLYING CONCEPTS: HOW COULD YOU USE DENSITY TO DETERMINE WHETHER A BAR OF METAL IS PURE GOLD?

If the bar of gold has a density that is greater than or less than 19.3 g/cm³, then the sample is not pure gold.

Densities of Some Common

Substances

Substance

Density(g/cm³)

Air 0.001

Ice 0.9

Water 1.0

Aluminum 2.7

Gold 19.3

FACTORS THAT AFFECT DENSITY

1. Add “something” to a liquid or gas to increase it’s density.

1. Ex. Adding sugar or salt to water

2. Temperature – increase the temperature and the density will decrease.

1. “warm air rises”

3. Changing the pressure.

FLOATING AND SINKING

An object will float if it is less dense than a surrounding liquid.

An object will sink if it is more dense than a surrounding liquid.

The density of water is 1 g/mL. If an object has a density of greater than 1 g/mL

it will sink in water. If an object has a density less than 1 g/mL it will

float in water.