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!

Work and Energy

  1. Feb 26, 2014 #1
    1. The problem statement, all variables and given/known data
    W = f x D
    W = work
    f = force
    D = distance

    What happens when the applied force is not constant?

    I have no idea. Can anyone please answer?
    Thank you.
  2. jcsd
  3. Feb 26, 2014 #2
    Do you know how the force varies with time? Is there a function that expresses this?
  4. Feb 26, 2014 #3
    No. Its just a research question that just ask what happens when the applied force is not constant.
  5. Feb 26, 2014 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    W = F*D is only valid for a constant force and distance measured in the direction in which the force acts. There is a more general equation relating a variable force to distance and work. Properly, it involves calculus and vectors. Not sure what level you're at.
    Ignoring the vector aspect, consider the force advancing a small distance ds, so that the force can be taken as not varying enough to matter. Then add up all these contributions over the total distance moved.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted