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Getting Celsius from Fahrenheit: Water freezes at 0 degrees Celsius, which is the same as 32 degrees Fahrenheit. Also water boils at 100 degrees Celsius, which is the same as 212 degrees Fahrenheit. a. Use the freezing and boiling points of water to find a formula expressing Celsius temperature \(C\) as a linear function of the Fahrenheit temperature \(F\). b. What is the slope of the function you found in part a? Explain its meaning in practical terms. c. In Example 3.5 we showed that \(F=1.8 C+32\). Solve this equation for \(C\) and compare the answer with that obtained in part a.

Short Answer

Expert verified
a. Formula: \(C = \frac{5}{9}(F - 32)\), b. Slope: \(\frac{5}{9}\), which means 1 F change equals \(\frac{5}{9}\) C change, c. Both solutions match.

Step by step solution

01

Set up two points

First, identify the two points that represent the freezing and boiling points of water. The point for freezing can be given as (32, 0), and the point for boiling is (212, 100), where the first number in each pair is Fahrenheit and the second is Celsius.
02

Calculate the slope

Use the formula for the slope \(m\) of a line using the points \((x_1, y_1)\) and \((x_2, y_2)\):\[m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{100 - 0}{212 - 32} = \frac{100}{180} = \frac{5}{9}\]The slope of this line is \(\frac{5}{9}\).
03

Write the linear equation

Now, use the slope-intercept form of a line \(y = mx + b\). We use the point-slope form using the point (32, 0):\[C - 0 = \frac{5}{9}(F - 32)\]Simplifying the equation gives:\[C = \frac{5}{9}(F - 32)\]
04

Interpret the slope

The slope \(\frac{5}{9}\) implies that for every increase of 1 degree Fahrenheit, the Celsius temperature increases by \(\frac{5}{9}\) degrees. This reflects the conversion rate between the two temperature systems.
05

Solve for Celsius in given equation

Given the equation \(F = 1.8C + 32\), solve for \(C\) by isolating \(C\):\[F - 32 = 1.8C\]\[C = \frac{F - 32}{1.8}\]Convert \(1.8\) to fraction form \(\frac{9}{5}\) to show it matches the derived equation:\[C = \frac{5}{9}(F - 32)\]This is the same as the equation derived in part a.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Linear Function
Simple and neat, a linear function represents a straight line in math, where two variables change together in a consistent pattern. This pattern is often represented by the equation \(y = mx + b\). Here, \(m\) is the slope and \(b\) is the y-intercept.
In the context of temperature conversion, the relationship between Fahrenheit and Celsius is a perfect example of a linear function.
  • The Fahrenheit and Celsius scales increase and decrease at a steady rate concerning each other.
  • These scales have two key points that form the basis of the linear relationship.
By establishing the freezing point of water as 32°F (0°C) and the boiling point as 212°F (100°C), we set the foundation to create a linear equation to describe their relationship.
Once you have two points, you can write the linear equation representing the change from Fahrenheit to Celsius or vice versa.
Slope Calculation
To find the slope, we use the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\).
This tells us how much one unit of change in Fahrenheit affects Celsius  essentially, the rate of change between the two temperature scales.
Our key temperatures were:
  • Freezing: (32, 0)
  • Boiling: (212, 100)
With these points, the slope calculation becomes \(m = \frac{100 - 0}{212 - 32} = \frac{100}{180} = \frac{5}{9}\).
This slope signifies that every increment of 1°F translates to an increment of \(\frac{5}{9}\)°C. That's how we find a direct correlation between the Fahrenheit and Celsius scales.
Celsius and Fahrenheit
Celsius and Fahrenheit are both units for measuring temperature, but they differ in their scale and origin. Celsius, based on the metric system, centers around the freezing (0°C) and boiling points (100°C) of water.
Fahrenheit, developed by Daniel Gabriel Fahrenheit, is more intricate, with 32°F marking the freezing point and 212°F the boiling point.
The heart of our conversion task is to transform Fahrenheit values into Celsius. The derived linear formula is critical:
\[C = \frac{5}{9}(F - 32)\]
This formula offers a straightforward way to convert Fahrenheit temperatures to Celsius, adjusting for the differences in scale and zero points.
Mathematical Modeling
Mathematical modeling comes into play in various everyday applications, like predicting outcomes or solving real-world problems using math. In our case, we're modeling the temperature conversion between Celsius and Fahrenheit.
The idea is simple:
  • Create a mathematical representation (equation) that describes the relationship.
  • Test its reliability using known reference points.
  • Use this model to predict and convert between temperatures effectively.
We derived the formula \(C = \frac{5}{9}(F - 32)\) using a basic linear function model.
This is a valid example of utilizing mathematical modeling to address practical needs, like converting weather forecasts or laboratory readings between different temperature units.

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