Www.calhoun.k12.al.us



Celsius to Fahrenheit.

Making an Equation for Conversion

(GLX)

Introduction:

Over the years different scientist have developed ways of calibrating temperature scales (Fahrenheit °F, Celsius °C, and Kelvin K). However, temperature values for these different scales are usually not consistent. Water freezes at 0°C on the Celsius scale, 32 °F on the Fahrenheit scale, and at 273K on the Kelvin scale. In fact it turns out that 90°C is hotter than 180°F and 250 K is colder than both. Thus these different temperature scales can sometime be very confusing.

There are equations scientists use to convert values from one scale to another so that we can easily compare values from the different temperature systems. For example if we were to convert from °C to K we would use the equation:

K = °C + 273.15

However, the equation for converting from Celsius to Fahrenheit if not as easy. You need to do more than just add a number to one to get the other. Their relationship is thus, more complicated.

Purpose:

To determine the equation for converting Celsius to Fahrenheit. To do this we must first find out what kind of mathematical relationship exists between the two variables and this is done by making a graph.

Materials/Equipment:

GLX

2 Temperature Probes

Hot and Cold Water

250 mL beaker

PROCEDURE

1. TURN ON THE GLX AND OPEN THE CELSIUS TO FAHRENHEIT FILE USING THE INSTRUCTIONS BELOW.

a. Turn on the GLX [pic]and select Data Files using your[pic] [pic] and press [pic]to select. Use your arrow[pic] [pic]to arrow up and over to Flash memory. Arrow down to the C to F file. Press F1[pic] to open the file. Press the Home key[pic].

2. Plug a Temperature probe into Port 1 and another into Port 2. Make certain the temperature probes are plugged in tightly.

3. You’ll want to watch that data being collected, so press [pic], Tables.

4. You are now ready to collect temperature data from both temperature probes. Set up 4 different temperature baths using beakers. You may share with other groups, but you want four different temperature baths. You can make a cold one with ice and water and a hot one with warm tap water or a microwave.

5. Start collecting data:

a. Press [pic] button to begin data collection.

b. Place both temperature probes into one of the water baths and wait for a minute or two for the two temperature probes to stabilize. You can monitor this on the table screen.

c. Move the two temperature probes to the next bath and repeat until you have all four data points collected.

d. Select [pic]when you have finished collecting data.

6. Press [pic].

7. Choose [pic], Graphs. You should see a graph of Temperature (F) vs. Celsius (C). Make certain that the run number on your graph corresponds to the run number from your table. You may need to use your [pic]and [pic] [pic]to select the correct run for this trial.

5. a. To find the slope and y intercept Choose [pic], Tools

b. Select Linear Fit, use your directional keys to extend to all your data points.

c. Record the Slope and the y-intercept.

Name _________________________

Partner’s Name(s) _________________________

Period ______Date_______________

Use this information to answer the questions.

PROCESSING THE DATA

FOR THE EQUATION OF A STRAIGHT LINE:

Y = aX + b (Equation 1)

1. What was the slope (a) of the line?

2. What was the y-intercept (b) of the line?

3. We plotted Fahrenheit on the Y-axis and we plotted Celsius on the X-axis. Rewrite (Equation 1) substituting the symbols for degree Fahrenheit and degree Celsius for Y and X respectively:

(Equation 2)

4. Now rewrite equation 2 substituting in the values you got for the constants (a) and (b).

(Equation 3)

5. Using your equation, calculate the following values. How close to the known values are the values you calculate?

a) 37o C = _____ oF

b) 212oF = _____ oC

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download