Measurement-A Common Language

EQ: How do I define mass, weight and density?

Mass

• The measure of the amount of matter an object contains

• Matter: The material that all objects and substances are made up of

• Anything that has mass and takes up space is matter

EQ: How do I define mass, weight and density?

•International System of Units–Abbreviated as SI after its French name Systeme International

•The basic unit of mass in the SI system is the kilogram.

EQ: How do I define mass, weight and density?

Units of Mass

Milligrams

•Used to measure smaller objects such as a paper clip

EQ: How do I define mass, weight and density?

Conversions

1 kg = 1,000 g

1 g = 1,000 mg

EQ: How do I define mass, weight and density?

Mass

Measuring Mass

How does a triple-beam balance work?

• A triple-beam balance works by comparing the mass of the object you are measuring to a known mass

• When you use a triple-beam balance, you:

1. Place the object on the pan2. Shift the riders on the beams until they balance

the mass of the object• Start with the large rider (increments of 100)• Next, the medium sized rider (increments of

10)• Lastly, the small rider (increments of 1)

EQ: How do I define mass, weight and density?

Mass

The Difference Between Mass and Weight

Weight

•The measure of the force of gravity acting on an object

EQ: How do I define mass, weight and density?

How would your weight differ if you were to travel to the moon?

• If you were to travel to the moon your weight would be less.

• Your weight would be lesser because the force of gravity is less.

• Weight is a factor of the force of gravity EQ: How do I define mass, weight and

density?

Why would your mass stay constant if you were to travel to the moon?

• Your mass would stay the same if you were to travel to the moon because mass is the amount of matter that an object contains

• Since you are still made up of the same amount of “stuff”, your mass would not change EQ: How do I define mass, weight

and density?

Why use the mass of an object instead of its weight?

• mass does not change when the force of gravity does

EQ: How do I define mass, weight and density?

Volume

•The amount of space an object takes up

EQ: How do I define mass, weight and density?

•Liter (L) –used to measure the volume of a liquid.

•Milliliter (mL) - To measure the volume of smaller liquids

EQ: How do I define mass, weight and density?

The instrument used to measure the volume of liquids is called the…

• Graduated cylinder.

EQ: How do I define mass, weight and density?

This instrument has markings that are in increments of…

• 1 milliliter (mL)

EQ: How do I define mass, weight and density?

Meniscus

• The curve in the top surface of water in the graduated cylinder

EQ: How do I define mass, weight and density?

What is the proper way to read a meniscus?

• Read the milliliter marking at the bottom of the curveEQ: How do I define mass,

weight and density?

Volume of a solid object

• To measure a solid objects that are regular shaped, a formula for volume can be applied

• To measure a rectangular object such as a shoebox, multiply the object’s length, width, and height

EQ: How do I define mass, weight and

density?

The SI unit known for measuring solids with a larger volume is known as the…

• Cubic meter (m³) - The SI unit used to measure solids with a larger volume

EQ: How do I define mass, weight and density?

Common Conversions For Volume

1 L = 1,000 mL

1 L = 1,000 cm³

1 mL = 1 cm³

EQ: How do I define mass, weight and density?

The formula for calculating the volume of a rectangular object is:

Volume = Length x Width x Height

EQ: How do I define mass, weight and density?

Why is the unit cm³ used when calculating the volume of a rectangular object?

• When multiplying the object’s length, width and height, the cm units are also multiplied

cm x cm x cm = cm³

EQ: How do I define mass, weight and density?

Suppose a cereal box is 10 centimeters long, 4 centimeters wide, and 20 centimeters high. What would be the volume of the box?

Volume = Length x Width x Height

Volume = 10 cm x 4 cm x 20 cm

Volume = 800 cm³EQ: How do I define mass, weight and density?

Volume of an Irregular Solid

• Water displacement method

• To measure the volume of an irregular solid, immerse the object in water, and measure how much the water level rises

EQ: How do I define mass, weight and density?

Steps for the water displacement method

• Record the volume of water in the graduated cylinder

• Carefully place the irregular solid into the water. Record the volume of the water plus the object

• Subtract the volume of the water alone from the volume of the water plus the object EQ: How do I define mass, weight and density?

Density

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

•The density of a substance is the same for all samples of that substance.

EQ: How do I define mass, weight and density?

The formula of density is:

Density = Mass / Volume

EQ: How do I define mass, weight and density?

Why is density expressed as a combination of two different units?

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

EQ: How do I define mass, weight and density?

Two Common Units For Density

• Grams per cubic centimeter (g/cm³)

• Grams per milliliter (g/mL)

EQ: How do I define mass, weight and density?

Math Practice: What is the density of a wood block with a volume of 125 cm³ and a mass of 57 g?

Density = mass / volume

Density = 57 g / 125 cm³

Density = 0.46 g/ cm³

EQ: How do I define mass, weight and

density?

Math Practice: What is the density of a liquid with a mass of 45 g and a volume of 48 mL?

Density = mass / volume

Density = 45 g / 48 mL

Density = 0.94 g/mLEQ: How do I define mass, weight and density?

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

Densities of Some Common Substances

Substance

Density(g/cm³)

Air 0.001

Ice 0.9

Water 1.0

Aluminum 2.7

Gold 19.3

EQ: How do I define mass, weight and density?

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

EQ: How do I define mass, weight and density?

Will an object with a density of 0.7 g/cm³ float or sink in water?

• An object that has a density of 0.7 g/cm³ will float in water (1 g/cm³) because it is less dense than water

EQ: How do I define mass, weight and density?