Convection

Convection

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When you heat a pot of water what happens?

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Multiple Choice

When you heat a pot of water, it

• condenses

• boils

• melts

• disappears

Where in the pot does the boiling first begin?

At the top? In the middle? At the bottom?

Poll

The boiling starts at the

• top

• middle

• bottom

• all of the above.

Boiling starts closest to the heat source, the bottom.

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Red-Orange=hot. Blue-Grey=cool

Multiple Select

The more heat, the more the molecules

• expand

• slow down

• speed up

• contract

Remember density?

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Less dense substances float.

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What do we learn form this graph?

See next slide

Multiple Choice

The graph shows that

• as temperature decreases, density decreases

• as temperature increases, density decreases.

Multiple Select

When boiling a pot of the water, the water at the bottom becomes

• the hottest

• more dense

• less dense

• a gas

• a liquid

The water at the bottom becomes hotter and therefore, less dense.

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Less dense objects float to the top

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Multiple Choice

What will happen to the hotter, less dense water? It will

• sink

• evaporate

• rise

• melt

Hot, less dense water rises to the top of the pot.

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Cold air is dense.

Dense air sinks.

Multiple Choice

What happens to the cooler, denser water?

• it rises

• it becomes a solid

• it becomes a gas

• it sinks

The hot, less dense air rises, while the cooler, denser air falls. This creates a circular, cycle of motion.

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The same is true for the air in our homes.

This circular cycle of motion has a name; CONVECTION

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