Question

Difficulty: MediumExtrapolation and Trend Prediction

A student measured the speed of sound in a chamber filled with pure carbon dioxide (CO2CO_2) gas at various temperatures. The measured speed of sound, in meters per second (m/s\text{m/s}), at each temperature, in degrees Celsius (C^\circ\text{C}), is shown in the table below:

Temperature (C^\circ\text{C})Speed of Sound (m/s\text{m/s})
00259259
2020268268
4040277277
6060286286

Assuming the speed of sound continues to change at a constant rate with respect to temperature, what is the predicted speed of sound in CO2CO_2 gas, in meters per second (m/s\text{m/s}), at a temperature of 100C100^\circ\text{C}?

Answer: 304 m/s

Answer

The predicted speed of sound in carbon dioxide gas at 100C100^\circ\text{C} is 304 m/s304\text{ m/s}.
The speed of sound increases linearly by 9 m/s9\text{ m/s} for every 20C20^\circ\text{C} increase in temperature, which is a rate of 0.45 m/s0.45\text{ m/s} per 1C1^\circ\text{C}. The target temperature of 100C100^\circ\text{C} is 40C40^\circ\text{C} higher than the highest data point in the table (60C60^\circ\text{C}). The speed of sound will therefore increase by 40×0.45=18 m/s40 \times 0.45 = 18\text{ m/s} beyond the 60C60^\circ\text{C} speed. Adding this to 286 m/s286\text{ m/s} yields 304 m/s304\text{ m/s}.

Step-by-Step Solution

1
Determine the constant rate of change of the speed of sound per 1C1^\circ\text{C} temperature increase.
The speed of sound increases at a rate of 0.45 m/s0.45\text{ m/s} per 1C1^\circ\text{C}.
This establishes the linear trend shown in the experimental data.
2
Find the temperature interval between the highest measured data point and the target temperature.
The difference is 40C40^\circ\text{C} (from 60C60^\circ\text{C} to 100C100^\circ\text{C}).
This determines how far outside the measured data range the extrapolation must extend.
3
Multiply the temperature interval by the rate of change and add it to the speed of sound at the highest measured temperature.
286 m/s+(40C×0.45 m/s/C)=304 m/s286\text{ m/s} + (40^\circ\text{C} \times 0.45\text{ m/s/}^\circ\text{C}) = 304\text{ m/s}.
This completes the linear extrapolation to predict the final value.

Key Concept

Linear extrapolation relies on determining a constant rate of change from the given data points and applying it to a target value outside the experimental range.
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