Lesson plan
Mpemba effect
The Mpemba effect is the observation that very hot liquids or colloids (such as ice cream) can freeze more quickly than colder ones, for similar volumes and surrounding conditions. The effect is named after Erasto Mpemba, a Tanzanian teenager who studied it scientifically in the 1960s for the first time, along with Denis Osborne. The Mpemba effect was initially observed in only ice cream and water, and later in other colloids. It has also been studied in magnetic alloys, nanomechanical systems, and quantum systems. In some colloids, a "strong" Mpemba effect is observed, where starting in certain hot temperature ranges leads to freezing much faster than starting in a cooler range. The effect is not observed in all environments or experimental setups. Studies of the effect in water have mixed results, with some experiments finding no reproducible effect. Physicists remain divided on the effect's precise definition and underlying mechanisms.
Article summary
The Mpemba effect is the observation that very hot liquids or colloids (such as ice cream) can freeze more quickly than colder ones, for similar volumes and surrounding conditions. The effect is named after Erasto Mpemba, a Tanzanian teenager who studied it scientifically in the 1960s for the first time, along with Denis Osborne. The Mpemba effect was initially observed in only ice cream and water, and later in other colloids. It has also been studied in magnetic alloys, nanomechanical systems, and quantum systems. In some colloids, a "strong" Mpemba effect is observed, where starting in certain hot temperature ranges leads to freezing much faster than starting in a cooler range. The effect is not observed in all environments or experimental setups. Studies of the effect in water have mixed results, with some experiments finding no reproducible effect. Physicists remain divided on the effect's precise definition and underlying mechanisms.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.