Density

ACTIVETEACH.COMKEY STAGE 3 MATHEMATICS (YEAR 7)

These two containers A and B have the same capacity. A is filled with sand and B is filled with beads.

We say that sand is more dense than beads.

We note that container B will be easier to lift than container A

mass

volumeDensity =

Mass = density x volume

Volume =mass

Density

A B

Density, mass and volume are connected by the relationships:

Density, mass and volume are connected by the relationships:

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A bag of salt measuring 5 cm x 6 cm x 7 cm weighs 218 grams. What is the density of the bag?

Density is amount of mass per unit volume.

Density =mass

volumeStep 1: calculate the volumeStep 1: calculate the volume

Volume = 5 cm x 6 cm x 7 cm

= 210 cm3

Step 2: Use formula to find the density

Step 2: Use formula to find the density

Density =218 g

210 cm3

= 1.04 g/cm3 (to 2 decimal places)

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A block of wood has with a density of 0.3 kg/cm3 is shown below. Calculate the mass of this block of wood in a) kg b) grams

Volume = 2.5 x 4 x 5 = 10 cm3

Mass = density x volume = 0.3 x 10 = 3 kg

3 kg = 3000 grams

4 cm

5 cm2.5 cm

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The mass of this block of wood is 9 kg.

Volume = x x = cm3

Density = = g/cm3

25 cm

30 cm15 cm

MARK ITMARK IT

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The mass of this block of wood is 9 kg.

Volume = x x = cm3

Density = = 0.8 g/cm3

25 cm

30 cm15 cm

15 3025

9000

11250

11250

9 kg = 9000 grams9 kg = 9000 grams

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