A quick lesson on how to convert between
temperatures in degrees Fahrenheit and degrees Celsius
Converting between units of measure or scales is a nice use of algebraic formulas.
When a formula represents one quantity (such as temperature in degrees
Fahrenheit) in terms of another quantity (such as temperature in degrees
Celsius), it shows a functional relationship. Thinking of algebra in terms of
functions like this helps algebra make sense.
If you don't want to compute with fractions, use a calculator or make a computer
spreadsheet. Better yet, use the mental technology you always have with you (in your
head), and learn the mental shortcuts below.
| To convert from Celsius to Fahrenheit: Multiply
the temperature in degrees Celsius by 9/5, then add 32 (degrees) to find the temperature
in degrees Fahrenheit.
*A mental shortcut for a rough estimate:
Double the temperature given in Celsius and add 30 to the result to find the
approximate temperature in Fahrenheit. |
To convert from Fahrenheit to Celsius:Subtract
32 (degrees) from the temperature in degrees Fahrenheit, then multiply by 5/9 to find the
temperature in degrees Celsius.
*A mental shortcut for a rough estimate:
Subtract 30 from the temperature given in Fahrenheit and take half of the result to
find the approximate temperature in Celsius.
|
Can you explain why these shortcuts work?
|
If you want to remember these formulas or the shortcuts, think of the temperatures
for freezing and boiling water in Celsius (0 and 100) and Fahrenheit (32 and 212) as
a reminder of whether to add or subtract and whether to multiply by 5/9 or 9/5. And
don't forget that the mental shortcuts only give a rough estimate.
|
Some sample conversions (Can you justify the last three?):40 º C = ? º F
>>>>> F
= 9/5 x 40 + 32 = 72 + 32 = 104 º F
35 º C = 95 º F
30 º C = 86 º F
25 º C = 77 º F
Try the following conversions:
20 º C = ? º F
? º C = 100 º F
38 º C = ? º F
? º C = 32 º F
|
