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How can I memorize temp and pressure conversions

  1. Mar 28, 2014 #1
    I am learning how to do temperature and pressure conversions for a process technology class. do you have any advice that can help me memorize how to do this stuff? How did you learn to memorize this stuff and was it hard for you to memorize?
  2. jcsd
  3. Mar 28, 2014 #2

    Simon Bridge

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    You mean converting between different units?
    It's a serious pain. usually I get the order mixed up - I can get it by remembering some common values.
    i.e. room temp = 20C = 72F so the F values need to be bigger .

    I have trouble memorizing fractions but I can recall a sentence so I write conversions on one line like:
    5(F-32) = 9C = 9(K-274)

    But 9/5 is almost 1/2 so, for smallish numbers F = about 2C+32

    Basically play to your strengths: what sort of stuff is easy to remember.
    But really - these are not difficult formulae requiring mnemonics or other memory tricks.
    It's like learning a phone number.
  4. Mar 28, 2014 #3
    Yea like converting Psi to psig or Celsius to kelvin. I can do it if I look at my cheat sheet but I think I am going to Need to memorize it.
  5. Mar 28, 2014 #4

    Simon Bridge

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    If you are doing lots then you probably do need to memorize them. yep.
    Fiddle about with the cheat sheet looking for patterns ... also, read through the sheet in bed just before turning out the light, then see how many you remember first thing in the morning when you wake up.

    But they are really just like phone numbers - does anyone remember phone numbers these days?
  6. Mar 28, 2014 #5
    Do what the rest of us did. Use your cheat sheet until you don't need it any more.

  7. Mar 28, 2014 #6
    Best way for C to F is this:

    2*C - (2*C/10) + 32

    so 20 C would be:

    2*20 = 40
    (2*20)/10 = 4
    40-4 = 36
    36 +32 = 68 F (72 F is more like 22 C)

    It's very easy to do in your head.

    F to C is a bit more difficult, and slightly less accurate:

    [(F - 32)/2] + [(F - 32)/2]/10

    so X=(F-32)/ 2
    18/10 = 1.8
    18+1.8 = 19.8, which is pretty close to 20.

    EDIT (fyi, the actual calc would be (F-32)/2 * 10/9, or the more formal (5/9)*F-32, but that's not done quickly in the head, the one above is a quick, and close, approximation)

    For other conversions, yea, just use a cheat sheet until you've used it enough that the conversions come easier. Try to first memorize some common/milestone values. (For instance 1 psi to kPa, 100 psi to kPa, etc) so that you at least can estimate the order of magnitude. Accuracy will come with practice.
    Last edited: Mar 28, 2014
  8. Mar 28, 2014 #7


    Staff: Mentor

    Some of us do. I can remember the phone number at the house my family lived in between '54 and '58... SU 3-4594. I don't know why that one has stuck, but it has.
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