AQA GCSE Physics (8463), Higher tier · Energy › Conservation and dissipation of energy
Practise Energy transfers in a system. 19 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Complete the sentence. The higher the thermal conductivity of a material, the .................... the rate of energy transfer by conduction through the material.
higher
A student thinks that a thicker layer of bubble wrap around a beaker of hot water will reduce the rate of cooling more than a thinner layer. Write a hypothesis for an investigation into this idea.
The thicker the layer of bubble wrap, the lower the rate of cooling.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Energy is transferred when a cyclist rides a bicycle.
(a) Which statement about energy is correct? Tick (✓) one box.[1]
Energy can be created but not destroyed.
Energy can be destroyed but not created.
Energy cannot be created or destroyed.
Energy is used up when it is transferred.
(b) The cyclist oils the bicycle chain regularly. Explain how oiling the chain reduces unwanted energy transfers.[2]
(c) What happens to the energy that is wasted? Tick (✓) one box.[1]
It is destroyed.
It is dissipated to the surroundings.
It is stored in the chemical store of the cyclist.
It is transferred back to the kinetic store of the bicycle.
Show the answer and mark scheme
(a)Answer: Energy cannot be created or destroyed.
(b)Answer: Oil (lubrication) reduces friction between the moving parts, so less energy is dissipated to the thermal store of the chain and surroundings.
(lubrication) reduces friction (between the moving parts)
so less energy is dissipated / wasted / transferred to the thermal store (of the chain or surroundings)
(c)Answer: It is dissipated to the surroundings.
Question 2Medium5 marks
A student thinks that a thicker layer of bubble wrap around a beaker of hot water will reduce the rate of cooling more than a thinner layer.
(a) Write a hypothesis for an investigation into this idea.[1]
(b) State the independent variable and the dependent variable in this investigation.[2]
(c) State two variables the student should control.[2]
Show the answer and mark scheme
(a)Answer: The thicker the layer of bubble wrap, the lower the rate of cooling.
the thicker the (bubble wrap) insulation, the lower the rate of cooling / the smaller the temperature decrease in a given time
(b)Answer: Independent: thickness (number of layers) of bubble wrap. Dependent: rate of cooling (temperature decrease in a fixed time).
independent variable: thickness / number of layers of bubble wrap
dependent variable: rate of cooling / temperature decrease in a fixed time
(c)Answer: Any two from: volume of water; starting temperature; type/size of beaker; room temperature.
volume of water
starting temperature of the water
type / size of beaker
room temperature
Question 3Hard6 marks
A student wants to find out how the thickness of a layer of newspaper wrapped around a beaker affects the rate at which hot water in the beaker cools.
Plan an investigation the student could do. Your plan should give valid results.[6]
Show the answer and mark scheme
Answer: Wrap the beaker in different numbers of layers of newspaper; same volume and starting temperature of water, same lid; measure the temperature at the start and after a fixed time; repeat for each thickness; compare temperature decreases or plot a graph.
wrap the beaker in a known number of layers of newspaper, e.g. 1, 2, 3, 4 and 5 layers (to vary the thickness)
pour the same volume of hot water into the beaker each time, measured with a measuring cylinder
use the same starting temperature each time, e.g. 80 °C, measured with a thermometer
use the same lid / cardboard cover each time
record the temperature after a fixed time, e.g. 10 minutes, timed with a stopwatch (or every minute)
calculate the temperature decrease for each thickness
repeat for each thickness and calculate a mean
plot a graph of temperature decrease against number of layers
take care with hot water, e.g. place the beaker on a heatproof mat
Marked with levels of response: the full level descriptors are in the app.