An ice cube usually melts faster on metal than on wood when both surfaces start at the same room temperature. Metal is a better conductor of heat, so it can transfer heat to the colder ice more quickly.
The MOE Primary Science syllabus covers good and poor conductors of heat. This example separates the temperature of an object from the rate at which it transfers heat.
- Check the starting temperatures.
- Identify which object is warmer than the ice.
- Explain which material transfers heat faster.
- Keep the comparison fair.
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Follow the direction of heat transfer
Both plates are warmer than the ice. Heat is transferred from each plate to the ice. The ice gains heat and melts. The metal plate conducts heat to the area touching the ice more readily than the wooden plate does.
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Worked example | Two plates start at 25°C
Place identical ice cubes on a metal plate and a wooden plate that have both been in the same room long enough to reach 25°C. Suppose the ice on metal melts first. A clear answer names the material, the heat transfer and the result. The metal is a better conductor of heat, so it transfers heat to the ice faster and the ice melts sooner.
If the metal feels cooler to your hand before the test, that sensation is also about heat transfer. The metal can draw heat from your warmer hand more quickly. The two plates can still have the same temperature.
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Make the comparison fair
Use pieces of ice with the same size and shape. Start the tests together, in the same place and away from direct sunlight. Use flat plates of comparable dimensions and check their starting temperatures. If one plate was chilled before the test, let it return to room temperature before comparing the materials.
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Frequently asked questions
Does the ice send cold into the plate?
Describe the transfer as heat moving from the warmer plate to the colder ice.
What can a parent ask before giving the answer?
Ask the child to draw an arrow for the heat transfer in each setup. Then ask which arrow represents the faster transfer and why.