Thermal insulation and cooling sim
The student wraps a beaker of hot water in different materials, reads the thermometer every minute, and compares the cooling curves to find the best insulator.
Thermal processes · covers the O-Level, IGCSE, GCSE topic
What the sim shows
Hot water loses energy by conduction through the beaker wall and wrapping, convection in the air around it, radiation from its surfaces and evaporation from the open top. A good insulator traps air, which conducts heat poorly, so less energy is conducted through the wall. A lid stops convection currents and evaporation from the surface. Shiny foil emits less radiation but does little about conduction or convection. The water cools faster when it is much hotter than the room, so each curve gets less steep as it nears 22 °C. Model: Newton's law of cooling, m c dθ/dt = −UA (θ − 22 °C), where m = 0.2 kg of water, c = 4200 J/(kg °C), θ is the water temperature and UA is the heat-loss rate per degree for each set-up, from 0.50 W/K (no wrapping, no lid) down to 0.125 W/K (foam sleeve with a lid). Bare beaker, no lid: 80 → 62.6 °C in 10 min, a drop of 17.4 °C. Energy lost = m c Δθ = 0.2 × 4200 × 17.4 = 14.6 kJ, about 24 W on average. With a lid the drop is 13.9 °C; with a foam sleeve and a lid only 5.0 °C. Why real results differ: the thermometer lags the water by about 10 s, it is read to the nearest 0.5 °C with small reading errors, and real open beakers lose more by evaporation when very hot. Simplified: the heat taken up by the glass and the wrapping is ignored, evaporation is part of a fixed lid-off term, water lost as steam is ignored and the room stays at 22 °C. Time only moves on when you press "Wait 1 minute".
- Thermometer: read the top of the red column to the nearest 0.5 °C
- Wrapping round a 250 cm³ beaker of 200 cm³ hot water
- Graph: your recorded readings for each run, joined by lines
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