1. Not finding help here? Sign up for a free 30min 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!

Finding work done on object with a chnaging force

  1. Oct 13, 2008 #1
    1. The problem statement, all variables and given/known data

    A single force acts on a 5.0 kg particle-like object in such a way that the position of the object as a function of time is given by x = 3.0t - 4.0t ^2 + 1.0t ^3, with x in meters and t in seconds. Find the work done on the object by the force from t = 0 to t = 2.0 s.



    2. Relevant equations

    W=Fd

    3. The attempt at a solution
    I started by finding the derivative of x = 3.0t - 4.0t ^2 + 1.0t ^3 which would be the velovity of the particle like object. (v=3-8t+3t^2)Then I plugged in 0 for when time=0 to find the velocity and then plugged in 2 for t to find the velocity when t=2 seconds. I then used the equation W=.5m(v^2-vo^2) to find that W=20 Joules however this was wrong
    What am I doing wrong?
     
  2. jcsd
  3. Oct 13, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Be careful with signs.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?