# Density - PowerPoint PPT Presentation

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Density. Grade 9 science. What is Density?. Density is a PHYSICAL property of matter It is a Quantitative property as it can be measured It is a way of comparing “heaviness” of objects It is the heaviness (mass) compared to a specific volume. Each box has the same volume.

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Density

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## Density

### What is Density?

• Density is a PHYSICAL property of matter

• It is a Quantitative property as it can be measured

• It is a way of comparing “heaviness” of objects

• It is the heaviness (mass) compared to a specific volume.

Each box has the same volume

If each ball has the same mass which cube will weigh more?

### Which is heavier?

• 1Kg of Feathers or 1Kg of Lead?

• Both weigh the same but the feathers will take up a lot more space (volume) than the same amount of lead.

• Why?

• The lead is more dense….

### Density calculated

• Since density is a comparison of mass to volume these two measurements are needed.

• Density = Mass (grams)

Volume (millilitres)

D = M

V

### Calculating Mass

• The mass of an object can be measured using a Balance.

### Calculating Volume

• Can be measured if the object is regular shape.

• Volume of a Cube =

length X width X height.

• Cylinder = πr2 X height

### What about odd shaped objects?

Archimedes figured it out….

### Calculating volume by Displacement.

An object placed into an overflow can will displace its own volume of water which can then be measured.

The volume is measured in mL or cc (cubic centimeters)

### Problem.

Is Julie’s ring pure gold?

### The G.R.A.S.P. or G.R.A.S.S. method

• Given

• Required to find

• Analysis

• Substitution

• Paraphrase (final answer) OR Solution

### Example

• A piece of iron has a volume of 12m3

and a mass of 94,800kg. What is the density of the iron.

G. V= 12m3

M= 94,800kg

• Density of Iron

• D = m

V

• S. D = 94,800kg

12m3

S. Density = 7,900kg/m3

Convert to g/cm3 1kg = 1000g.

1m3 = 1000cm3 Therefore answer =

7.9g/cm3