From a magazine article in the early 70's

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Lxnxjxhx

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C > F > C

1. Going from C to F or from F to C?
Doesn't matter! Add 40.

2. F > C? Multiply by 5/9. (or 1/2)
C > F? Multiply by 9/5. (or 2)

3. Do the opposite of step 1.
 

Dennis Alwon

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Staff member
Location
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Occupation
Retired Electrical Contractor
Lxnxjxhx said:
C > F > C

1. Going from C to F or from F to C?
Doesn't matter! Add 40.

2. F > C? Multiply by 5/9. (or 1/2)
C > F? Multiply by 9/5. (or 2)

3. Do the opposite of step 1.

Are we talking farenheit & Cel. I thought it was 5/9 +32, or 9/5 -32.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Dennis is right. Remember that Centigrade (Celsius) is based on the freezing and boiling points of water.

If you start with F, you subtract 32 to get the freezing point of water to 0, which makes the top of the scale 180 (212-32). Then you divide by 9 and multiply that by 5, which accounts for the 9:5 ratio of 180:100.

To convert C to F, divide by 5, then multiply by 9 (restoring the 100:180 ratio), then add the 32. Remember, you always add or subtract the 32 while in the "Farenheit" side of the equation.
 
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Lxnxjxhx

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No. No 32 degree stuff.
That's the whole idea of this formula; it's based on -40C equaling -40F.
Try it! It's way easier to remember than that other way.

E.g., 20 C = 68 F.

20 + 40 = 60
9/5 x 60 = 540/5 = 108
108-40 =68.

68 + 40 = 108
5/9 x 108 = 540/9 = 60
60-40 = 20

Man, I just don' get no respek!
 

Dennis Alwon

Moderator
Staff member
Location
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Occupation
Retired Electrical Contractor
I don't get the 5/9 or 1/2, and the 9/5 or 2. They are not the same and in the example above we get

20 + 40 = 60
60 * 2= 120
120-40= 80

It doesn't work and it's not even close.

BTW I had my 9/5 and 5/9 reversed in the previous post and I just notice Trevor had it correct.
 

mdshunk

Senior Member
Location
Right here.
crossman said:
Simple, basic algebra manipulation.
Fletch: “It's so simple, maybe you need a refresher course!”
Fletch: “It's all ball bearings nowadays!”
Fletch: “Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads!”
Fletch: “And I'm gonna need about 10 quarts of antifreeze, preferably Prestone. No, no, make that Quaker State.”
 

zog

Senior Member
Location
Charlotte, NC
Oh yeah?

Think of a number between 1 and 10 (Not 1 or 10)

Multiply it by 9

Take the 2 digits of your number and add them together

Find the letter of the alaphabet that corresponds with your number (A=1, B=2, C=3, etc)

Think of a country that BEGINS with your letter

Take the LAST letter of you country and think of an animal that BEGINS with that letter

Take the LAST letter of your animal and think of a color that BEGINS with that letter.

Now go read Post #5 in the thread "Wire Sizing"
 
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zog

Senior Member
Location
Charlotte, NC
mdshunk said:
Fletch: ?It's so simple, maybe you need a refresher course!?
Fletch: ?It's all ball bearings nowadays!?
Fletch: ?Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads!?
Fletch: ?And I'm gonna need about 10 quarts of antifreeze, preferably Prestone. No, no, make that Quaker State.?

"May i borrow your towel? My car just hit a water buffalo"
 

crossman

Senior Member
Location
Southeast Texas
Example

(9/5)C + 32 = F

Add 40 to both sides

(9/5)C + 72 = F + 40

Take 9/5 out of the 72 -----> 72 = (9/5) x 40

(9/5)C + (9/5)(40) = F + 40

Combine the common factor

(9/5)(C + 40) = F + 40

Subtract 40 from both sides

(9/5)(C + 40) - 40 = F

It definitely works.
 

crossman

Senior Member
Location
Southeast Texas
Dennis Alwon said:
I don't get the 5/9 or 1/2, and the 9/5 or 2.

The 1/2 and the 2 are just approximations of 5/9 and 9/5 and as you say, are not all that accurate. Use 9/5 and 5/9 and the OP formulas work, again, it is basic algebraic manipulation.
 
L

Lxnxjxhx

Guest
or just a mad scientist tinkerer?

or just a mad scientist tinkerer?

I can tell you I'm way more disgruntled than I was this morning! It's easier to sell iceboxes to Eskimos.

Speaking of mad, here's a book for you.

http://www.amazon.com/Electronic-Ci...=sr_1_8?ie=UTF8&s=books&qid=1210285880&sr=1-8

They tell you how to make these gadgets, then they tell you how to modify them to make them lethal. And the designs are credible.
I gotta' wonder who funded this research. . .
 

realolman

Senior Member
Lxnxjxhx said:
I can tell you I'm way more disgruntled than I was this morning! It's easier to sell iceboxes to Eskimos.

Speaking of mad, here's a book for you.

http://www.amazon.com/Electronic-Circuits-Evil-Genius-Cutcher/dp/0071448810/ref=sr_1_8?ie=UTF8&s=books&qid=1210285880&sr=1-8

They tell you how to make these gadgets, then they tell you how to modify them to make them lethal. And the designs are credible.
I gotta' wonder who funded this research. . .

I dunno ... didn't seem all that evil to me. Maybe antisocial. :smile:
 

jghrist

Senior Member
zog said:
Oh yeah?

Think of a number between 1 and 10 (Not 1 or 10) 8

Multiply it by 9 72

Take the 2 digits of your number and add them together 9

Find the letter of the alaphabet that corresponds with your number (A=1, B=2, C=3, etc) I

Think of a country that BEGINS with your letter Iran

Take the LAST letter of you country and think of an animal that BEGINS with that letter Newt

Take the LAST letter of your animal and think of a color that BEGINS with that letter. Tan

Now go read Post #5 in the thread "Wire Sizing"

Doesn't work every time:mad: The amazing part is how hard it was to think of an animal that started with "N".
 

zog

Senior Member
Location
Charlotte, NC
jghrist said:

Doesn't work every time:mad: The amazing part is how hard it was to think of an animal that started with "N".

Oops, I missed a step. you need to subtract 4 before picking the letter,
 

LawnGuyLandSparky

Senior Member
mdshunk said:
Fletch: ?It's so simple, maybe you need a refresher course!?
Fletch: ?It's all ball bearings nowadays!?
Fletch: ?Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads!?
Fletch: ?And I'm gonna need about 10 quarts of antifreeze, preferably Prestone. No, no, make that Quaker State.?

That was only after leaving his palatial imitation apartment building...
 
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