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The Cold Metal Spoon Brain Teaser
A metal spoon and a wooden spoon have been lying on the same kitchen table all day, so they are at exactly the same temperature. Yet when you pick them up, the metal spoon feels much colder. Why?
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What's the puzzle?
A metal spoon and a wooden spoon have been lying on the same kitchen table all day, so they are at exactly the same temperature. Yet when you pick them up, the metal spoon feels much colder. Why?
What's the answer?
Metal is a better thermal conductor, so it carries heat away from your hand faster
How do you work it out?
- Both spoons are at room temperature, which is cooler than your hand, so heat flows from your hand into each spoon.
- Your skin senses how fast heat is leaving it, not the actual temperature of the object.
- Metal is a good thermal conductor, so it carries heat away from your hand quickly. Wood is a poor conductor (an insulator), so it carries heat away slowly.
- The metal spoon feels colder because it conducts heat away from your hand faster than the wooden spoon does.
Frequently asked questions
Is the metal spoon actually colder than the wooden spoon?
No. After a day on the same table, both spoons are at room temperature. The metal spoon only feels colder because it conducts heat away from a warm hand faster than wood does.
What is a thermal conductor?
A thermal conductor is a material that lets heat energy pass through it easily, such as most metals. A thermal insulator, such as wood or plastic, lets heat pass through slowly. LoveMaths Tutoring UK uses the cold metal spoon puzzle to illustrate the difference.
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