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: Finding Change in Kinetic Energy

  1. Dec 4, 2011 #1
    1. The problem statement, all variables and given/known data
    A mass of 8.50 kg is travelling 7.50 m/s
    [up]. It is acted on by a force of 340 N [up]
    over a displacement of 15.0 m [up].

    What is the change in kinetic energy

    2. Relevant equations
    Ek = 1/2mvsquared. F = mv. w = fd

    3. The attempt at a solution

    I tried doing the equation Ek = 1/2mvsquared, and was off by 3000 or so.
  2. jcsd
  3. Dec 4, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    That's because you probably used the INITIAL speed. The speed will change, because there is a force acting on the object.

    1. Figure out the work done on the object (don't forget to consider all forces acting on it).

    2. Use the work-energy theorem to figure out the object's change in kinetic energy given the work done in part 1.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook