1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

B Equation dealing with energy?

  1. Dec 5, 2017 #1
    What is
    ΔEp = ΔEk + W
    I have come across this formula, but i haven't seen it before. What is it used for?
  2. jcsd
  3. Dec 5, 2017 #2


    User Avatar
    Gold Member

    Δ is used to mean a change in something, so
    Change in Ep = Change in Ek + W

    Beyond that I'm stuck unless the person who composed the formula tells me.

    I could guess the E stood for energy and the subscripts p and k stood for potential and kinetic.
    W might then stand for work.

    But that is a total guess, since formulae are made up by people according to their own mathematical needs. An equation or formula without context has no definite physical meaning.

    Edit 3. Oh, you asked about use. If it is something like the meaning I guessed, then you might use it to calculate changes in potential energy and kinetic energy when work is done on a body. But you'd have to be very careful to measure the variables suitably, as this formula would not take account of the signs of the quantities. A better formula to use might be ΔPE = W - ΔKE

    (edits 1& 2 were typographical)
    Last edited: Dec 5, 2017
  4. Dec 5, 2017 #3


    User Avatar
    Gold Member

    And there you go! I guessed wrong. Try looking at laws of Thermodynamics. That seems to be the context where formulae using these symbols occur when I search in Google.

    Sorry to have it wrong.

    Lets hope Chestermiller, is around. He's a whizz on thermodynamics.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Threads - Equation dealing energy Date
I An equation for fire Mar 6, 2018
I Deriving the wave equation Feb 24, 2018
B Faulty velocity equation? Feb 24, 2018
I Equations to model tennis ball motion Feb 22, 2018
I How do you deal with commas in vector equations Jun 13, 2016