alleryStart learning →Why are the walls of a cool box made of thick foam?
- Foam slows energy transfer
- Foam speeds energy transfer
- Foam adds mass to the box
- Foam keeps the box upright
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Correct answer: A. Foam slows energy transfer
1. A cool box has to stop energy from the warm air outside reaching the food.
2. Materials that slow energy transfer are called insulators.
3. Foam is a good insulator, so a thick foam wall keeps the inside cold longer.
4. A material that sped up the transfer would be a conductor and would spoil the food.
_Source: Siyavula Natural Sciences Grade 7 (CC BY 4.0), Why do we need insulating materials?_