2.1.1 Try some yourself
Activity 6
The table below indicates the cooling rate of tea in a teapot.
| Time/mins | 0 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
| Temperature/°C | 90 | 65 | 60 | 50 | 36 | 35 | 30 | 26 | 25 | 22 | 20 |
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(a) How long does it take for the tea to cool to 50°C?
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(b) By how much does the temperature drop in the first 20 minutes? By how much does it drop in the second 20 minutes?
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(c) How would you describe the pattern of cooling?
Answer
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(a) 15 minutes.
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(b) The temperature drops from 90°C to 36°C in the first 20 minutes, a total of 54 degrees. In the second 20 minutes, the temperature drops from 36°C to 25°C, a total of 11 degrees.
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(c) The tea cools quickly at the beginning when it is hot, then cools more slowly when it is cooler.
OpenLearn - Diagrams, charts and graphs
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