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!

Dynamics/energy problem

  1. Jun 29, 2009 #1
    I was wondering if someone could check if the following is correct: A
    box of mass M is tied to a propeller with an upward force of F. Ignore
    weight of propeller. The box is placed on a vertical spring that is initially
    at equilibrium and then the propeller is ignited. The spring constant is K.
    Find speed after the spring has moved by a distance of X. So would I do:
    K_{initial} = 0; U_{initial} = 0; U_{spring} = 0 initially. Kf = 1/2*mv^2
    ; U_{final} = MgX;U_{spring} = 1/2*kX^2.
    And the total work done by the force F is F.x, or at the distance X, FX.
    So since the total work done is equal to the change in mechanical energy, so
    I write: FX = 1/2*mv^2 +MgX + 1/2*KX^2 and solve for v? Thank you.
  2. jcsd
  3. Jun 29, 2009 #2


    User Avatar
    Homework Helper

    I see that the spring is not compressed at the start. So yes, the equation as you have written it looks right.
  4. Jun 29, 2009 #3
    Oh right, thanks!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Dynamics/energy problem
  1. Energy and/or dynamics (Replies: 2)

  2. Dynamic problem (Replies: 1)

  3. Dynamics problem (Replies: 8)

  4. Dynamics wagon problem (Replies: 9)