New
New
Year 11
•
Higher
Combining densities
I can combine compound measures, calculating overall density.
New
New
Year 11
•
Higher
Combining densities
I can combine compound measures, calculating overall density.
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Lesson details
Key learning points
- Two densities can be combined to give an overall density.
Keywords
Density - The density of a substance is measured as the substance's mass per unit of volume.
Common misconception
Pupils understand they multiply by 100 when converting m to cm, but when converting m^3 to cm^3, fail to recognise the need to multiply by 100^3.
Illustrate a 1m^2 square and the equivalent 100cm^2 square, calculating the area and allowing pupils to see the equivalence of 1 m^2 = 10 000 cm^2. Also apply this to a 1m^3 and 100cm^3, thus allowing students to see 1m^2 = 100 000 cm^3.
We use combining of densities everyday. Discuss with pupils when have they combined different densities today. This gives pupils the opportunity to appreciate the importance of combining densities. Furthermore, looking at metals, discuss of the benefits of combining metals to make alloys.
Teacher tip
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Starter quiz
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6 Questions
Q1.
The of a substance is measured as the substance's mass per unit of volume.
speed
volume
pressure
Correct answer: density
density
mass
Q2.
A metal block has a mass of 600 grams and a volume of 200 cm$$^3$$. What is the density of the metal?
0.3 g/cm$$^3$$
120 000 g/cm$$^3$$
Correct answer: 3 g/cm$$^3$$
3 g/cm$$^3$$
30 g/cm$$^3$$
Q3.
A rectangular block has a density of 2.5 g/cm$$^3$$, a length of 10 cm, a width of 4 cm, and a height of 5 cm. What is the mass of the block? Give your answer in g.
Correct Answer: 500, 500 g, 500g
500, 500 g, 500g
Q4.
A cylinder has a radius of 3 cm, a height of 10 cm, and is made of a material with a density of 7.8 g/cm$$^3$$. What is the mass of the cylinder? Give the answer in g to the nearest integer.
Correct Answer: 2205, 2205 g, 2205g
2205, 2205 g, 2205g
Q5.
A piece of wood has a mass of 240 grams and a density of 0.6 g/cm³. What is the volume of the wood? Give your answer in cm$$^3$$.
Correct Answer: 400 , 400 cm^3, 400cm^3
400 , 400 cm^3, 400cm^3
Q6.
Put the following densities in order, starting with the densest at the top.
1 - Osmium has a mass = 22 600 kg and a volume = 1 m$$^3$$
1
- Osmium has a mass = 22 600 kg and a volume = 1 m$$^3$$
2 - Iridium has a mass = 1120 kg and a volume = 0.05 m$$^3$$
2
- Iridium has a mass = 1120 kg and a volume = 0.05 m$$^3$$
3 - Platinum has a mass = 64.5 kg and a volume = 0.003 m$$^3$$
3
- Platinum has a mass = 64.5 kg and a volume = 0.003 m$$^3$$
4 - Gold has a mass = 1.93 kg and a volume = 0.0001 m$$^3$$
4
- Gold has a mass = 1.93 kg and a volume = 0.0001 m$$^3$$
5 - Silver has a mass = 21 000 kg and a volume = 2 m$$^3$$
5
- Silver has a mass = 21 000 kg and a volume = 2 m$$^3$$
Exit quiz
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6 Questions
Q1.
What are the benefits when combining metals to make an alloy compared to pure metals?
Correct answer: The alloy can be stronger.
The alloy can be stronger.
Correct answer: The alloy can provide greater resistance to corrosion.
The alloy can provide greater resistance to corrosion.
Correct answer: The alloy can improve durability.
The alloy can improve durability.
Every alloy becomes shinier.
Every alloy is more expensive than its parts.
Q2.
A block of metal A has a mass of 400 g and a volume of 50 cm$$^3$$. A block of metal B has a mass of 300 g and a volume of 75 cm$$^3$$. What is the combined density of the two metals?
Correct answer: 5.6 g/cm$$^3$$
5.6 g/cm$$^3$$
5.5 g/cm$$^3$$
5.4 g/cm$$^3$$
5.3 g/cm$$^3$$
Q3.
Liquid X has a density of 1.2 g/cm$$^3$$ and a volume of 100 cm$$^3$$. Liquid Y has a density of 0.8 g/cm$$^3$$ and a volume of 150 cm$$^3$$. What is the combined density of liquid X and Y?
1 g/cm$$^3$$
1.1 g/cm$$^3$$
Correct answer: 0.96 g/cm$$^3$$
0.96 g/cm$$^3$$
0.98 g/cm$$^3$$
0.9 g/cm$$^3$$
Q4.
A piece of wood (density 0.5 g/cm$$^3$$, volume 100 cm$$^3$$) is glued to a piece of plastic (density 1.4 g/cm$$^3$$, volume 50 cm$$^3$$). What is the average density of the combined piece?
Correct answer: 0.8 g/cm$$^3$$
0.8 g/cm$$^3$$
0.85 g/cm$$^3$$
0.95 g/cm$$^3$$
0.9 g/cm$$^3$$
Q5.
An alloy is made by combining 3 kg of metal K (density 5 g/cm$$^3$$) with 2 kg of metal L (density 3 g/cm$$^3$$). What is the density of the alloy in g/cm$$^3$$? Give your answer to 1 s.f in g/cm^3.
Correct Answer: 4, 4 g/cm^3, 4g/cm^3
4, 4 g/cm^3, 4g/cm^3
Q6.
A tank contains 2 litres of oil (density 0.9 g/cm$$^3$$) and 3 litres of water (density 1 g/cm$$^3$$). What is the density of the mixture in kg/m$$^3$$?
Correct Answer: 960, 960 kg/m^3, 960kg/m^3
960, 960 kg/m^3, 960kg/m^3