density. what is density? if someone called you dense…what would they mean?

Density

What is density?

If someone called you dense…what would they

mean?

What is density?

Density is a comparison of how much matter there is in a certain amount of space…it is a ratio!

What is density?

Density is a comparison of how much matter there is in a certain amount of space…it is a ratio!

So…what arithmetic is associated with a ratio?

What is density?

Usually we think of population density when we talk about density.What is population density?

What is density?

Usually we think of population density when we talk about density.What is population density?

It is the number of people per squarekilometer…or in English…per square mile.

What is density?

Which state has the highest population density…the most people per square kilometer?

Which state has the least population density…the fewest people per square kilometer?

Which one is more dense?

A

B

Now Which one is more dense?

A

B

What is density?

Density = mass OR mass ÷ volume. volume

Units for density: g or g. cm3 mL

(cm3 ≈ mL)Why are there different units for density?

Always remember to

label your answer using SI

units!

We are going to solve for density in a very structured way for awhile. We are going to use GUESS!

STEPS FOR SOLVING FOR A VARIABLE

G: given; What information is given in the word exercise?

U: unknown; What is being asked for in the word exercise?

E: equation; What formula will you use to solve the word exercise?

S: substitution; Replace the letters with units given in the word exercise.

S: solution; Write down the answer, number and unit.

Let’s do an exercise together.(Why did I just call a density word exercise an exercise?)

*Alecia has a watch. It has a mass of 63g and a volume of 6cm3. What is the density of the watch?

*Alecia has a watch. It has a mass of 63g and a volume of 6cm3. What is the density of the watch?G -U - E -S -S -

*Alecia has a watch. It has a mass of 63g and a volume of 6cm3. What is the density of the watch?G - m = 63 g, v = 6 cm3

U -E -S -S -


U - densityE -S -S -

.


U - densityE - density = m/vS - S -


U - densityE - density = m/vS - d = 63 g/ 6 cm3

S -


U - densityE - density = m/vS - d = 63 g/ 6 cm3

S - 10.5 g/cm3

Now…check your density table. What do you think Alecia’s watch was made of?

Now…check your density table. What do you think Alecia’s watch was made of?

That’s right - - - - it’s made of silver!

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 – Try with your neighbor

Which liquid has the highest density?

Which liquid has the lowest density?

Which liquid has the middle density?

Liquid LayersCheck out this picture. 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?

Water is the standard for comparison when it comes to density.

Pure water has a density of 1.0 g/mL (since it is a fluid g/mL is the accepted unit to use as the label)

Keep in mind, though, that g/mL is equivalent to g/cm3!

That means we can compare densities to water easily.

For example:

if d > 1.0 g/mL - the object would sink in water

if d < 1.0 g/mL - the object would float in water

if d ≈ 1.0 g/mL - the object would mix with, or flink depending on it’s state

Super Scientist of the Day…

If a large gem was discovered with a volume of 36cm3,and a mass of 126.72g, what is its density and what is the identity of the gem?

If a large gem was discovered with a volume of 36cm3,and a mass of 126.72g, what is its density and what is the identity of the gem?

G:U:E:S:S:

density. what is density? if someone called you dense…what would they mean?

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