Density

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Density
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Demos for this lecture

• 1 kg mass (Is it heavy?)
• 50 ml of alcohol and 50ml of water in graduated
  cylinders on a double pan balance.

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Archimedes
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Archimedes and the Golden Crown
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Density

• Density is how compact matter is.
• More mass shoved into a certain amount of space
  makes something more dense.

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Density Considers Two Things

• How much mass is present.
• How much volume does it take up.
• Make sure to consider both these factors when
  discussing density.

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A
A
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1. What does Figure A illustrate about the density
   of the two metals? Explain.

A
A
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2. What does Figure B illustrate about the
density of the two metals? Explain.
A
A
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3. If the cube of aluminum in figure B were cut
into four equal parts. How would the density of
one part compare to the whole cube?
A
A
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4. Metals expand when heated. If the gold cube
in part B is heated, what will happen to its
density?
A
A
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Does it Float?

• If something floats or rises it is less dense
  than the material it is floating/rising in.
• Objects of greater density will sink.

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Density

• Density is the mass per unit volume.
• How much mass there is in a certain amount of
  space.

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Density

• Density is the mass per unit volume.
• Density Mass Volume

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Density

• Density is the mass per unit volume.
• D Mass Volume

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Solving For Variables
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Common Volume Units
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Mass 2680g Volume 1450cm3
Illegal ivory is often detected on the basis of
density. What is the density of the elephant
tusk?
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Illegal ivory is often detected on the basis of
density. What is the density of the elephant
tusk?
Mass 2680g Volume 1450cm3
D M V 2680g 1450cm3 1.8482g/cm3
1.85g/cm3
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Calcium chloride is used as a deicer on roads in
winter. Its density is 2.50g/cm3. What mass of
calcium chloride will the truck hold if its
volume is 4560L?
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Calcium chloride is used as a deicer on roads in
winter. Its density is 2.50g/cm3. What mass of
calcium chloride will the truck hold if its
volume is 4560L?
4560L 4,560,000cm3
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Calcium chloride is used as a deicer on roads in
winter. Its density is 2.50g/cm3. What mass of
calcium chloride will the truck hold if its
volume is 4560L?
4560L 4,560,000cm3
M D x V 2.50g/cm3 x 4,560,000cm3
11,400,000g 11,400,000g
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The density of methanol is 0.788g/cm3. What is
the minimum volume of a tank that can hold 795kg
of methanol.
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The density of methanol is 0.788g/cm3. What is
the minimum volume of a tank that can hold 795kg
of methanol.
795kg 795,000g
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The density of methanol is 0.788g/cm3. What is
the minimum volume of a tank that can hold 795kg
of methanol.
795kg 795,000g
V M D 795,000g 0.788g/cm3
1,008,883cm3 1,010,000cm3
How many liters is this?
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The density of methanol is 0.788g/cm3. What is
the minimum volume of a tank that can hold 795kg
of methanol.
1,010,000cm3 1000 cm3/L 1010L
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Homework

• Worksheet Chapter 2-3