Listen&Learn: Superfluids

The liquids that can flow forever.

Pre-listening vocabulary

• viscosity: the resistance that slows the flow of a liquid
• approach: to get closer to something
• absolute zero: the lowest possible temperature, where all particles stop moving
• atom: the type of particle that forms chemical elements
• friction: the resistance between two objects moving against each other
• collide: to crash or bump into something

Listening activity

Podcast: Play in new window | Download (Duration: 1:17 — 1.2MB)

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Gapfill exercise

A superfluid is a unique type of that has zero viscosity. This means that it will never stop flowing. The only type of liquid that scientists can turn into a superfluid is liquid helium. Helium is the only substance that stays in liquid form even as its approaches absolute zero. Most substances freeze at much higher temperatures. When liquid helium is at a very low temperature, all of its atoms have the same amount of . This causes the substance to behave like one single atom instead of many. The atoms in superfluid helium don’t collide with each other, or transfer energy to each other. Because of this, there is no friction between the helium atoms. If a decided to stir a container of superfluid helium, the liquid would continue to spin around the container .

Comprehension questions

Discussion/essay questions

1. Because a superfluid has zero viscosity, it can move through tiny cracks and holes that a regular liquid can’t. How might that be a problem for scientists experimenting with superfluid helium?

Transcript

A superfluid is a unique type of liquid that has zero viscosity. This means that it will never stop flowing. The only type of liquid that scientists can turn into a superfluid is liquid helium. Helium is the only substance that stays in liquid form even as its temperature approaches absolute zero. Most substances freeze at much higher temperatures. When liquid helium is at a very low temperature, all of its atoms have the same amount of energy. This causes the substance to behave like one single atom instead of many. The atoms in superfluid helium don’t collide with each other, or transfer energy to each other. Because of this, there is no friction between the helium atoms. If a scientist decided to stir a container of superfluid helium, the liquid would continue to spin around the container forever.