The Science of Everyday Life
Why metal spoons feel cold, how ABS shortens stops, and what really makes a microwave heat your dinner. Fifty questions on the physics hiding in plain sight.
Try 3 questions
1. A microwave oven heats food mainly because microwaves cause water molecules to do what?
- Absorb radiation and become mildly radioactive
- Rotate back and forth as the field flips, creating friction
- Split apart into hydrogen and oxygen atoms
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Answer: Rotate back and forth as the field flips, creating friction
Water molecules are polar, so the rapidly alternating electromagnetic field makes them twist; the resulting molecular jostling shows up as heat. No chemical bonds are broken and nothing becomes radioactive.
2. Why does a refrigerator make the kitchen slightly warmer overall, even though it cools its interior?
- It moves heat outward and adds the energy used by the compressor
- It destroys heat inside but the door seal leaks warm air inward
- It converts electricity directly into cold, releasing light as waste
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Answer: It moves heat outward and adds the energy used by the compressor
A fridge is a heat pump: it relocates heat from inside to the coils outside, and the electrical work done by the compressor is also dumped into the room as heat. The net effect on a closed kitchen is warming.
3. Two identical pots of water sit on a stove in Mexico City (2,240 m) and in Cartagena (sea level). What differs?
- Boiling temperature is identical; only the time differs
- Water boils at a higher temperature in Mexico City
- Water boils at a lower temperature in Mexico City
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Answer: Water boils at a lower temperature in Mexico City
Boiling happens when vapour pressure equals atmospheric pressure. At altitude the air pressure is lower, so water boils near 92°C, which is why foods take longer to cook there.
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