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Physics · 2.2 Thermal processes · Paper 6 practical

Cooling Curves. Insulate it.

Investigate how an insulating material affects the rate at which hot water loses thermal energy. Measure the temperature of hot water at regular intervals; plot the cooling curve and compare insulators.

0625 Topic 2.2.2 — Thermal energy transfer 0625 Topic 2.2.3 — Consequences Paper 6 — ATP
Setup — pick an insulator and initial temperature, then press Start cooling to begin.
00:00
Temperature 85.0 °C · Insulator none

Readings auto-record every 60 s. Shortcuts Space start/pause · R reset.

Variables

—
85
22
200
60

Live readouts

Time elapsed
0 s
Water temperature
85.0 °C
Drop from start Δθ
0.0 °C
Cooling rate (last interval)
— °C/min
Newton's law of cooling: dθ/dt ∝ (θ − θ_amb). Curve flattens as θ approaches θ_amb.

Trial data — auto-recorded at each interval

Press Start cooling. Readings are auto-recorded every interval.

θ vs t — cooling curve

📋 Method (Cambridge ATP procedure)
  1. Pour a fixed volume (e.g. 200 cm³) of boiling water into a beaker wrapped in the chosen insulating material.
  2. Place the thermometer in the water, stir gently, and wait for the temperature to maximise before starting the timer.
  3. Start the stopwatch and record the temperature θ at t = 0.
  4. Record the temperature at regular intervals (e.g. every 60 s) for 10 minutes. Stir gently before each reading.
  5. Repeat the entire procedure with each insulating material in turn, ensuring the same volume of water and initial temperature.

Analytical control: plot θ (y) against t (x) for each insulator on the same axes. The slowest-falling curve indicates the most effective insulator.

⚠ Sources of error & precautions
  • Heat loss before t = 0 — wait for the temperature to peak before timing; otherwise the curve starts low.
  • Uneven heat distribution — stir gently before each reading.
  • Different surface areas — use identical beakers for fair comparison.
  • Ambient drafts — perform the experiment away from open windows or fans.
  • Thermometer position — keep the bulb fully submerged, not touching the bottom or sides.
  • Parallax when reading the thermometer — view perpendicular to the mercury/alcohol column.
🧪 Apparatus list
  • Identical glass beakers (one per insulator)
  • Insulating materials: cotton wool, bubble wrap, aluminium foil
  • Liquid-in-glass thermometer (−10 °C to 110 °C, ± 1 °C)
  • Digital stopwatch (± 0.01 s)
  • Measuring cylinder (± 1 cm³)
  • Kettle of boiling water
  • Stirrer (glass rod)
🎯 Syllabus reference (0625)
  • 2.2.2 Conduction, convection and radiation — describe an experiment to compare insulating properties of materials.
  • 2.2.3 Consequences of energy transfer — explain how everyday devices reduce energy transfer (e.g. vacuum flask, double glazing).
  • Paper 6 — design a fair test; identify independent, dependent and control variables; record data in a table; plot a graph and draw a conclusion.

Ask the lab assistant