Results 1 to 7 of 7

Math Help - How to include the right units?

  1. #1
    Member
    Joined
    Oct 2011
    Posts
    153

    How to include the right units?

    Well I have a problem, about how when celsius increases, the fahrenheit will increase as well.
    I have a graph, showing my celcius as the manipulative variable (on the x-axis), while the fahrenheit is the responding variable (y-axis)

    So I used the slope equation, m=(change in y)/(change in x)
    So I grabbed 2 points and did m=(212oF-50oF)/(100oC-10oC) = 162oF/90oC
    I know that 162/90 = 1.80

    But I have 2 different units in the final solution, fahrenhait (oF) and celcius (oC)
    I always have to include the units so that when another person reads it, they would know what units I am talking about.

    So can anyone explain to me which units I would use? I wasn't sure to convert one measurement to another, cause that would start messing things up maybe.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2012
    From
    AZ
    Posts
    616
    Thanks
    97

    Re: How to include the right units?

    F = \frac{9}{5}C + 32

    This means, when C increases by 1, F increases by 9/5. And yes, the units will be \frac{^{\circ}F}{^{\circ}C}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2011
    Posts
    153

    Re: How to include the right units?

    Ok thanks!

    So once I try to find points on the graph, like an x coordinate or y coordinate.
    If I plug it into the linear equation: y=mx+b
    and since m=1.80oF/oC

    If I had to subtract it from Fahrenheit, how will the units become then?
    Since if I subtract m, into y so I could get x, y is Fahrenheit, while m is Fahrenheit over Celsius.

    Can anyone explain? Thanks
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,623
    Thanks
    428

    Re: How to include the right units?

    Quote Originally Posted by Chaim View Post
    So once I try to find points on the graph, like an x coordinate or y coordinate.
    If I plug it into the linear equation: y=mx+b
    and since m=1.80oF/oC

    If I had to subtract it from Fahrenheit, how will the units become then?
    Since if I subtract m, into y so I could get x, y is Fahrenheit, while m is Fahrenheit over Celsius.

    Can anyone explain?
    subtract what ? why would you want to subtract the slope?

    the equation is y^\circ F = \frac{9^\circ F}{5^\circ C} \cdot (x^\circ C) + 32^\circ F

    ... note that the equation makes the Celsius units cancel.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Oct 2011
    Posts
    153

    Re: How to include the right units?

    Thanks!
    I saw where my mistakes were now!

    So just wondering, if I was looking for an x coordinate, and I got a y coordinate, for example:
    I know Y = 70oF

    So I put it into the linear equation
    1. 70oF=(9oF/5oC)x + 32oF
    2. 350oFoC = (9oF)x + 32oF Multiply both sides by 5oC
    3. 38.88oC = x + 32oF Divide both sides by 9oF

    So I got 2 numbers equaled to each other, but they're both different units.
    Did I do something wrong or should I subtract 32 from both sides to find x?
    Thanks
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,623
    Thanks
    428

    Re: How to include the right units?

    Quote Originally Posted by Chaim View Post
    So just wondering, if I was looking for an x coordinate, and I got a y coordinate, for example:
    I know Y = 70oF ... then x would be in oC

    So I put it into the linear equation
    70oF=(9oF/5oC)x + 32oF ...
    70^\circ F = \frac{9^\circ F}{5^\circ C} \cdot x + 32^\circ F

    70^\circ F - 32^\circ F = \frac{9^\circ F}{5^\circ C} \cdot x

    38^\circ F = \frac{9^\circ F}{5^\circ C} \cdot x

    38^\circ F \cdot \frac{5^\circ C}{9^\circ F} = x

    notice the degrees F cancel, leaving degrees Celsius ...

    21.1^\circ C \approx x
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,530
    Thanks
    774

    Re: How to include the right units?

    Quote Originally Posted by Chaim View Post
    1. 70oF=(9oF/5oC)x + 32oF
    2. 350oFoC = (9oF)x + 32oF Multiply both sides by 5oC
    The right-hand side should be (9oF)xoC + 160oFoC.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. how can i include more in the exponent
    Posted in the LaTeX Help Forum
    Replies: 2
    Last Post: January 12th 2011, 07:57 AM
  2. Factors which include imaginary numbers
    Posted in the Algebra Forum
    Replies: 3
    Last Post: October 29th 2009, 02:01 PM
  3. Replies: 2
    Last Post: July 1st 2009, 12:29 PM
  4. Replies: 3
    Last Post: November 15th 2008, 04:18 AM
  5. Replies: 0
    Last Post: November 11th 2008, 09:27 PM

Search Tags


/mathhelpforum @mathhelpforum