1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    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!

Homework Help: Plotting singularity functions

  1. Sep 15, 2014 #1
    1. The problem statement, all variables and given/known data

    Can someone explain how the expression for V(x) is plotted?

    2. Relevant equations

    3. The attempt at a solution
    I understand the plots for the dotted lines but not how they got the actual plot for V(x)

    Attached Files:

  2. jcsd
  3. Sep 15, 2014 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It's been awhile since I did this but I think you just sum the dotted curves region by region.. I'll do the region shown in green on my copy of your diagram..

    At the start of the region you have..

    +8 from (a)
    -32 from (b)
    +0 from (c)
    +40 from (d)
    = +16

    Then at the end/right you have

    +8 from (a)
    -48 from (b)
    +16 from (c)
    + 40 from (d)
    = +16

    So in that region the result is a horizontal line at +16.

    Attached Files:

  4. Sep 18, 2014 #3
    thanks, I have another question:

    at x=6, I'm supposed to be getting V(x)=0 but summing the dotted curves, I get

    (23/4) -3(6) +3(3) + (1/6)(6^2) - (1/6)(3^2) + 2(3) + (7/4)

    Attached Files:

  5. Sep 19, 2014 #4


    User Avatar
    Science Advisor
    Homework Helper
    2017 Award

    Does that mean you think the exercise has been answered properly ? I think I see an ans (2) on the picture, but I have no idea what the question is!
    By the way: read the guidelines and fill in the template. Include an explanation of what <> [ ] and the superscripts 0 and 1 mean. That way others can read what this is about!

    You then post another question: "I'm supposed to be getting V(x)=0". Well, I get that too, but just by deciphering the funny code these authors use to indicate intervals and to describe V. Not by dallying around with 23/4 and all kinds of other fractions. What is this ? Where do you get these dashed lines from? What do they represent ?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted