CCEA GCSE Physics
CCEA GCSE Physics 1.3 Density and Kinetic Theory Exam Questions
Free CCEA GCSE Physics revision for 1.3 Density and Kinetic Theory: what you need to know, common mistakes and exam-style questions with answers. Covers density, measuring density of regular and irregular solids and liquids, and the kinetic theory of solids, liquids and gases.
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About CCEA GCSE Physics 1.3 Density and Kinetic Theory
Density and Kinetic Theory is a Unit 1 topic in CCEA GCSE Physics that links measurements of mass and volume to the arrangement of particles. You need to use density = mass / volume with both g/cm3 and kg/m3, and know how to measure the density of liquids, regular solids and irregular solids by displacement. The prescribed practical investigates the relationship between mass and volume. The kinetic theory explains the properties of solids, liquids and gases in terms of particle arrangement, spacing and movement, and why gases are much less dense. It links to heat transfer in 1.4. Examiners regularly test unit conversions and the displacement method.
What you need to know
- Density Density = mass / volume. Units are g/cm3 or kg/m3, and 1 g/cm3 = 1000 kg/m3. Water has a density of 1 g/cm3; objects less dense than water float.
- Regular solids and liquids For a regular solid, measure its dimensions with a ruler or callipers to find volume and weigh it on a balance. For a liquid, measure volume in a measuring cylinder and find its mass by weighing the cylinder empty and then with the liquid.
- Irregular solids Use displacement: fill a displacement (Eureka) can to the spout, lower the object in and collect the overflow in a measuring cylinder, or record the rise in level in a measuring cylinder. The volume displaced equals the volume of the object.
- Prescribed practical: mass and volume Measure the mass of increasing volumes of a liquid (or samples of a material) and plot mass against volume. A straight line through the origin shows mass is proportional to volume, and the gradient is the density.
- Kinetic theory Solids: particles closely packed in a regular arrangement, vibrating about fixed positions. Liquids: particles close together but irregular, able to move past each other. Gases: particles far apart, moving quickly and randomly in all directions.
- Explaining density differences Solids and liquids are much denser than gases because their particles are much closer together, so there is more mass in the same volume.
Common mistakes in 1.3 Density and Kinetic Theory
- Mixing units, such as dividing grams by cubic metres. Keep mass and volume in matching units.
- Converting g/cm3 to kg/m3 by multiplying by 100. The factor is 1000.
- Saying particles in a solid do not move. They vibrate about fixed positions.
- Reading a measuring cylinder from the top of the meniscus. Read from the bottom of the meniscus at eye level.
- Forgetting to subtract the mass of the empty container when finding the mass of a liquid.
Try three 1.3 Density and Kinetic Theory exam-style questions
1. A stone of mass 54 g is lowered into a measuring cylinder and the water level rises from 50 cm3 to 70 cm3. Calculate the density of the stone in g/cm3 and in kg/m3. (4 marks)
Show the mark scheme answer
Volume = 70 - 50 = 20 cm3; density = 54 / 20; = 2.7 g/cm3; = 2700 kg/m3.
2. Describe the arrangement and motion of the particles in a gas. (2 marks)
Show the mark scheme answer
Particles are far apart and randomly arranged; they move quickly in random directions.
3. Explain why steam is much less dense than water. (2 marks)
Show the mark scheme answer
Particles in steam (a gas) are much further apart; so there is less mass in the same volume.
1.3 Density and Kinetic Theory FAQs
What does CCEA GCSE Physics 1.3 Density and Kinetic Theory cover?
It covers density calculations, measuring the density of regular solids, irregular solids and liquids, and the kinetic theory model of solids, liquids and gases.
Which unit is 1.3 Density and Kinetic Theory examined in?
It is examined in the Unit 1 written paper, and the mass and volume practical can also be assessed in Unit 3 Practical Skills.
What do I need to remember about density units?
Learn both g/cm3 and kg/m3 and that 1 g/cm3 = 1000 kg/m3. Check that the mass and volume units match before dividing.
