Question 1 Hard
A cuboid has a mass of 0.60 kg and a volume of 2.0 × 10⁻⁴ m³. Calculate its density in kg/m³.
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Answer: 3000 kg/m³
- density = mass ÷ volume.
- 0.60 ÷ 0.00020 = 3000 kg/m³.
Density and thermal insulation practicals: GCSE Combined Science Physics practice questions
A second set of questions on density and thermal insulation practicals. They are different from the ones on the topic page. Try each, then open the answer and compare your working.
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Question 2 Hard
Two beakers of hot water start at 80 °C. After 10 minutes beaker A is at 70 °C and beaker B is at 62 °C. Which has the better insulation, and by how many degrees did the other cool more?
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Answer: A is the better insulator and B cooled 8 °C more
- A fell by 10 °C and B fell by 18 °C.
- The smaller fall means A has the better insulation, and B cooled 8 °C more.
Question 3 Hard
Explain why a lid is used on each beaker in a thermal insulation test.
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Answer: It reduces energy lost by evaporation and convection from the surface, so the test is fairer
- Energy is lost from the top of the water by evaporation and convection.
- The lid reduces this so the test mostly compares the insulation.
Question 4 Hard
Suggest one improvement to the density method for an irregular stone and explain why it improves the result.
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Answer: Repeat the measurements and take a mean, because this reduces the effect of random errors
- Repeating readings reduces the effect of random errors.
- Reading the meniscus at eye level removes a parallax error.
Quick checks
Short questions with options. Choose one before you open the answer.
Check 1
What is the equation for density?
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Density = mass ÷ volume.
Check 2
What are the units of density?
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Kilograms per cubic metre, kg/m³, or grams per cubic centimetre, g/cm³.
Check 3
How do you convert a density in g/cm³ to kg/m³?
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Multiply by 1000.
Check 4
What is the density of water?
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1.0 g/cm³, which is 1000 kg/m³.
Check 5
What happens to an object with a density greater than water?
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It sinks in water.
Check 6
How do you find the volume of a cuboid?
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Multiply the length, width and height.
Check 7
How do you find the volume of an irregular solid?
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Measure the volume of water it displaces.
Check 8
How do you read the volume in a measuring cylinder correctly?
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Put your eye level with the bottom of the meniscus.
Check 9
How do you find the mass of a liquid with a balance?
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Zero the balance with the empty measuring cylinder on it, add the liquid and read the mass.
Check 10
What is an insulator?
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A material that is a poor conductor of heat and slows the transfer of thermal energy.
Check 11
In an insulation test, what is the independent variable?
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The insulating material.
Check 12
In an insulation test, what is the dependent variable?
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The fall in temperature after a fixed time.
Check 13
Name three control variables for the insulation test.
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Starting temperature, volume of water and thickness of insulation.
Check 14
What does a flatter cooling curve show?
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The material is a better insulator, because the water cools more slowly.
Check 15
Why do materials with trapped air make good insulators?
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Air is a poor conductor, and trapped air cannot circulate to carry heat by convection.
Check 16
Why use a lid on the beaker in an insulation test?
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It reduces energy lost by evaporation and convection from the surface of the water.
Check 17
Name one safety precaution for the insulation test.
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Use water at about 80 °C, stand the beakers on a heatproof mat and wear eye protection.
Check 18
How can you reduce the effect of random errors in these practicals?
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Repeat the readings and calculate a mean.
Check 19
What is the density of a block with mass 54 g and volume 20 cm³?
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2.7 g/cm³.
Check 20
What is thermal conductivity?
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How well a material conducts heat. Insulators have a low thermal conductivity.
Check 21
Why can a cooling graph be better than a single reading?
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It shows how fast the temperature falls throughout the test, so you can compare the curves.
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