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

Dx as change in distance vs dx as infinitesimal x?

Tags:
  1. Feb 21, 2014 #1
    dx as change in distance vs dx as infinitesimal x???

    Why are they the same notation?


    Sent from my iPhone using Physics Forums
     
  2. jcsd
  3. Feb 22, 2014 #2
    Because they're the same thing. What meaning exactly would [itex] dx [/itex] have otherwise?

    If at time [itex] t [/itex] you have some position [itex] x(t) [/itex] then Newton's Law tells you how a small change in position is related to the velocity of the particle - namely [itex] x + dx = x + v(t)dt [/itex], where [itex] v(t) [/itex] satisfies the equation [itex] m\frac{dv}{dt} = F [/itex].
     
  4. Feb 22, 2014 #3

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    An actual change in distance is often denoted by δx or Δx, to distinguish it from the infinitesimal dx, which is part of Calculus. dy/dx really means the limit of δt/δx as δx approaches zero. In Science, we are often too sloppy about these notations as there may be pitfalls when you don't stick to the 'rules' precisely.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Dx as change in distance vs dx as infinitesimal x?
  1. Sound Vs. Distance (Replies: 2)

  2. U(x) = -du/dx (Replies: 8)

Loading...