Heat and temperature
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3. Thermal energy, temperature and mass. Q&A

Figure 7.2


Q: Look at the pot of soup and the tub of water in the figure above. Which do you think has greater thermal energy?


A: The soup is boiling hot and has a temperature of 100 °C, whereas the water in the tub is just comfortably warm, with a temperature of about 38 °C.
Although the water in the tub has a much lower temperature, it has greater thermal energy.

The particles of soup have greater average kinetic energy than the particles of water in the tub, explaining why the soup has a higher temperature.

However, the mass of the water in the tub is much greater than the mass of the soup in the pot.
This means that there are many more particles of water than soup.
All those moving particles give the water in the tub greater total kinetic energy, even though their average kinetic energy is less.

Therefore, the water in the tub has greater thermal energy than the soup.

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Q: Could a block of ice have more thermal energy than a pot of boiling water?

A: Yes, the block of ice could have more thermal energy if its mass were much greater than the mass of the boiling water.

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