Why we would 32 in Celsius to Fahrenheit & Vice Versa

[HussanAli]

Why we would 32 in Celsius to Fahrenheit & Vice Versa.

Hey fellows, please tell me why we add 32 to celsius to Fahrenheit conversion and vice versa. According to my mind, I derive C to F formula of my own. I do the following.1)I look and choose the same scale of F and C. The most obvious of which is freezing and boiling point. For F (32-212) and for C (0-100).2)Now to derive the formula for C to F, i divided 180/100 =1.8 it means that if celsius then the corresponding F is 1.8. So I now want to know how much is 37C in Fahrenheit then I multiplied it by 1.8*37=66.6 which is not true unless I add 32 to this. But why would I actually do that? Please explain 32 celsius to Fahrenheit.

 

[belliott4488]

You've correctly figured out the relative scales for F and C temperatures, i.e. the ratio of one degree C to one degree F, but since the two don't both start at the same zero point, you have to add 32 degrees, which is the amount of offset between them. In other words, if they both defined zero degrees to be the freezing point of water, but used their different scales, then you'd be fine, but since the Fahrenheit scale is offset by 32 degrees, you must account for that.

Maybe it would help you to draw a plot of F degrees vs. C degrees. You could have a line parallel line to the F line that went through the origin - that would correspond to what you would get with no offset. But the correct F line is offset by 32.

 

[HussanAli]

Thanks guy. =)

Formula
(32°C × 9/5) + 32 = 89.6°F

 

[MATLABdude]

The Celsius scale was based on the freezing and boiling points of water. The Fahrenheit scale was based on the freezing point of a brine solution and the temperature of the human body:
http://en.wikipedia.org/wiki/Fahrenheit