COS 12

Identify Metric Units for mass, temperature, and density.

Notes:Color Guide• Gold: Important concept. Write this down.

• Orange: Definition. Write this down.

• Blue: Important information, but you do not need to copy.

• Red: Example. Copy if needed.

• White: General Discussion (Don’t Copy)

Although there are many different branches of science, all scientists follow the same procedures.

Definition: critical thinking – the process of analyzing data & information to produce a solution.

Let’s try a few examples:

Would it be possible for a man to marry his widow’s sister?No, because the man is dead!

If you have only one match and you walked into a room where there was an oil burner, a kerosene lamp, and a wood burning stove, which one would you light first?

You should light the match first.

Data collection is especially important in science.• Data comes in all types. Some examples of data:– Temperature– Distance– Composition– Speed– Time

• Most data is described using a unit of measurement.– Definition: unit – a quantity used to measure data.

• Example: Centimeters is a unit that measures length or distance.

If I said that I had 58, would it mean anything to you?58 cents? Dollars? Bananas?

• Definition: base unit – a unit that cannot be broken down into other units. There are 7 base units.– Length/Distance: meter (m)– Mass: Kilogram (kg)– Time: second (s)– Temperature: Kelvin (K)– Volume: Liters (L)– Electric Current: Amp (A)– Molecular Weight: Mole (mol)

We will define these units as we come across them.

mkg

s

K

A

molL

m kg s K A mol L

• Definition: derived unit – a unit composed of 2 or more base units.There are many, many derived units. You may recognize

some, like area, volume, and speed.

– Example: km/h (kilometers per hour) is a derived unit.• Km/h is a unit of speed. It is derived from distance

and time.

Scientists use SI when they take measurements.–Definition: SI – a complete system of units for

scientists that is the same worldwide. Based on multiples of 10.• SI means “system international”.

–Some examples of NON-SI units:• Pounds• Inches• Feet• Miles• Ounces• Cups• Gallons

Most of these units are used only in the USA.

Many SI units are based on the metric system.Units can be made larger or smaller by adding a prefix.

– Definition: metric prefix – a name placed before a unit that changes the amount of that unit.

– Metric Prefixes:• Kilo (1000)• Hecto (100)• Deka (10)• Deci (.1)• Centi (.01)• Milli (.001)

KilogramPrefix Base Unit

Examples:• 5 kilograms is the same as 5000 grams.

• 10 centimeters is the same as .01 meters.• 10 millimeters is the same as 1 centimeter.

What is density?

• Density- is a comparison of how much matter there is in a certain amount of space.

What is density?

• Density = mass OR mass ÷ volume. volume

• Units for density: g . cm3

Volume can also be measured in (mL). 1mL = 1cm3

• Why are these the units for density?

ALWAYS REMEMBER

UNITS!

Let’s try a density problem together

• Frank has a paper clip. It has a mass of 9g and a volume of 3cm3. What is its density?

• Frank also has an eraser. It has a mass of 3g, and a volume of 1cm3. What is its density?

Work on these problems with your neighbor.

• Jack has a rock. The rock has a mass of 6g and a volume of 3cm3. What is the density of the rock?

• Jill has a gel pen. The gel pen has a mass of 8g and a volume of 2cm3. What is the density of the rock?

Now, try these on your own.

• Al’Licia has a watch. It has a mass of 4g and a volume of 2cm3. What is the density of the watch?

• Mia has a wallet. It has a mass of 15g and a volume of 5cm3. What is the density of the wallet?

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• Check out this picture from your

book. Which layer has the highest density?

• Which layer has the lowest density?• Imagine that the liquids have the

following densities: – 10g/cm3. 3g/cm3.– 6g/cm3. 5g/cm3.

• Which number would go with which layer?

Review

• What is the formula for density?• What happens if you pour together liquids

that have different densities?• Will the liquid on the top have the highest or

lowest density?• Will the liquid on the bottom have the highest

or lowest density?