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: Work problem

  1. Apr 5, 2008 #1
    "work" problem

    1. The problem statement, all variables and given/known data
    A force F(2xi+5yi)N acts on an object as it moves in the x direction from the origin to x=4.96m. Find the work W=integral vector F(dr) done by the force on the object

    2. Relevant equations

    3. The attempt at a solution

    integral 0 to 4.96 (2xi+5yi)N=2x^2/2|0 to 4.96=24.6

    integral 5yi=5y^2/2=5(4.96)/2=61.5


    Could someone please tell me if this is correct?

    Thank you very much
  2. jcsd
  3. Apr 5, 2008 #2

    Shooting Star

    User Avatar
    Homework Helper

    Incorrect. There's no displacement in the y, that is, j direction.

    Judging by your other posts on related topics, I would recommend another thorough reading up on this chapter.
  4. Apr 7, 2008 #3
    Would it be like this?

    Integral (2xi+5yj)(idx)|0 to 4.96=
    integral 0 to 4.96(2x)dx=
    2xx|0 to 4.56=
    2x^2|0 to 4.56=

    Work done in the y direction=0

    Total work=41.6J

    Thank you
  5. Apr 7, 2008 #4
    Integral of 2x is not 2x^2. Might want to recheck that.
  6. Apr 8, 2008 #5

    Shooting Star

    User Avatar
    Homework Helper

    It's a dot product: (2xi+5yj).(idx)

    (Why did it become 4.56?)

    Antiderivative of 2x is 2x^2/2.

    Correct your calculation.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook