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!

Work and kinetic energy

  1. Mar 1, 2008 #1
    The magnitude of a certain one-dimensional force varies according to:

    F = 6.68x^2 + 1.56

    where x is the displacement from the origin in meters, and F is the force in Newtons. At t = 0, a 677 g mass is at the origin moving in the positive x-direction at speed 8.46 m/s when this force begins to act on it.
    ASSUME: there are no other forces acting on the mass.

    a) How much work is done by the force on the mass when it reaches x = 2.78 m?
    b) What is the speed of the mass when it reaches 2.78 m?


    i put x=2.78 into the equation. w=(6.68*2.78^2)*2.78
    and get the wrong answer.

    3. The attempt at a solution
  2. jcsd
  3. Mar 1, 2008 #2

    Shooting Star

    User Avatar
    Homework Helper

    If you put the value of x, you get the force, not the work. Think about what is work done in terms of force and distance.
  4. Mar 1, 2008 #3
    not, i put the value of x. and get the force, then use the force * distance.w=(6.68*2.78^2+1.56)*2.78
  5. Mar 1, 2008 #4

    Shooting Star

    User Avatar
    Homework Helper

    When the force is not constant, then the work done is Integral(from x1 to x2)[Fdx].
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Work and kinetic energy
  1. Kinetic Energy&Work (Replies: 4)