2.5 The following readings were obtained in acooling experiment:
Temperature (8°C) 36.0 35.2 34.2 33.0 32.5 32.0 31.6 31.5 31.3 31.131.0
Time (min) 0 1 2
3 4 5 6 7 8 9 10
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Ra 0,4
Plot a graph of O against t. From the graph determine the time for the temperature to
fall from 35.0°C to 31.2°C. Measure the rate of fall of temperature at points 34.5, 33.2
and 31.2.
2.8 The two scientists Dulong and Petit found that the rate of loss of heat is
proportional to 0,", i. e.
2.38
Hence,
R= k0,
2.39
Where is the excess temperature, which is equalto:
0-OR
2.40
Where Or is the temperature of the surrounding; verify this law using the
appropriate graph (take O, to be 29°C). Find the slope and its attendant erro
What does the slope of this graph represent? / explain the implication of th
graph. (Use the Table in exercise 2.5 above).
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