Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why introduce a constant?

  1. Jul 11, 2009 #1
    My proff mentioned something about proportionality:
    "To make an a proportionality into an equality, we must introduce a constant"
    Something along those words: my question is why? Can show prove this to me??
     
  2. jcsd
  3. Jul 11, 2009 #2

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I am not aware of any proof of the concept, but I can offer a reason. Consider the statement "y is proportional to x". This means that a finite change in x induces a finite change in y. The size of the change in y depends on the size of the change in x. Now to quantify it, we need to introduce the so-called constant of proportionality. It is this constant that determines how big the change in y is for a given change in x.

    For example, take the equation y = 3x. Clearly y is proportional to x and if x changes by +1, then y changes by +3. Equally, consider the equation y = 2x. Once again, y is clearly proportional to x, but this time for each integer step of x, y changes by 2.

    This is why we need to introduce such constants. More technically, a proportionality defines a family of curves, by fixing the constant of proportionality (as well as the additive constant) you are effectively choosing a single curve from the family.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Why introduce a constant?
  1. Why -*-=+ (Replies: 3)

Loading...