GCSE Physics

AQA GCSE Physics (8463). Learn each topic step by step, then run the required practicals.

AQA GCSE Physics · Required practical · Energy

Thermal insulation

Investigate how the type and thickness of an insulating layer affects how quickly a beaker of hot water cools. Wrap the beaker, pour in 200 cm³ of hot water, then read the thermometer every minute.

250200 150100 50 250 ml ≈ 5% MINSEC1/10 00:00.0 START/STOPRESET EYE-LEVEL VIEW
Room temperature 20.5 °C Volume 200 cm³ Thermometer resolution 0.5 °C Set up the beaker, then pour.
Insulating material
Number of layers 1
Read every
Total time
Clock speed
Stopwatch0 s
Thermometer20.5 °C
Step 1 of 3 · choose the insulation

Results

Time / sTemp / °C
RunStart / °CEnd / °CDrop / °CRate / °C min⁻¹

Cooling curves

Temperature against time, every run
Method
  1. Wrap the outside of a 250 cm³ beaker with one layer of the insulating material and hold it in place with elastic bands.
  2. Measure 200 cm³ of hot water from the kettle and pour it into the beaker.
  3. Place a cardboard lid on the beaker and put the thermometer through the hole so the bulb sits in the water.
  4. Start the stopwatch and record the starting temperature.
  5. Record the temperature every minute for 10 minutes, reading the scale at eye level.
  6. Repeat with a different material, or with more layers of the same material, keeping everything else the same.
Variables
Independent
Type of insulating material (or the number of layers)
Dependent
Temperature of the water after each minute, giving the temperature drop over 10 minutes
Control
Volume of water (200 cm³), starting temperature, beaker size, lid on or off, total time, room temperature
Safety
  • Hot water can scald. Pour slowly with the beaker on a heat-proof mat and stand up while pouring.
  • Clamp the thermometer so it cannot roll off the bench; report any breakages straight away.
  • Mop up spills immediately and keep the kettle cable away from the edge of the bench.
Analysis questions

1. Which material was the best insulator? Use your temperature drops to justify your answer.

The best insulator gives the smallest temperature drop over the same time, because it reduces the rate of energy transfer from the water to the surroundings.

2. Why does the water cool fastest at the start?

The temperature difference between the water and the room is largest at the start, so the rate of energy transfer is highest. As the difference falls, the cooling slows and the curve flattens.

3. Suggest why the lid makes a difference.

The lid reduces energy transfer from the surface by convection and evaporation, so less energy leaves through the top of the beaker.

4. Why does adding more layers give a smaller improvement each time?

Energy is still transferred through the lid and the base, which the wrapping does not cover, so these losses stay the same however thick the wrapping is.