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A Melting Buffer for a Model Display 4 questions
A Melting Buffer for a Model Display
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A museum class tests two model samples for a display. One is a solid that melts near 28 °C and the other remains liquid over the test. Each sample gains energy at the same constant rate of 40 J per minute. The graph shows the temperature of each sample. The display’s test limit is 30 °C.
Question 1
At which plotted time is the reference above the limit while the buffer is still below it?
- 4 min
- 8 min
- 12 min
- 16 min
Question 2
Explain why the buffer can receive energy from minute 6 to minute 14 without a measured rise in temperature.
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Question 3
A student claims that the reference gains more energy than the buffer between minutes 6 and 14 because its temperature rises. Calculate the energy gained by each sample in that interval and evaluate the claim.
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The display needs a sample that stays near 28 °C for at least 12 minutes after melting begins. The class considers using twice the mass of the same pure buffer. It uses the same energy input rate and assumes that the energy needed to melt each gram is unchanged.
Question 4
Would twice the original mass meet the 12-minute requirement in this model? Use the graph and the energy needed per gram to explain.
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