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!

Energy Conservation & Potential Energy Spring/Friction Problem

  1. Mar 6, 2011 #1
    1. The problem statement, all variables and given/known data

    A 0.80-kg block is held in place against the spring by a 67-N horizontal external force. The external force is removed, and the block is projected with a velocity v1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity v2 = 1.9 m/s at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction is 0.39. The velocity of the block is v3 = 1.4 m/s at C. The block moves on to D, where it stops. In Fig. 7.4, the force constant of the spring is..

    [​IMG]

    2. Relevant equations

    K1 +U1 +W other = K2+ U2.. ect .. U2=0.5kx^2 .. K1=(0.5)mv^2

    3. The attempt at a solution

    I've tries solving the problem with the equation above but I really just don't know where to start especially since there are no units of distance given.. Can someone lead me in the right direction please?
     
    Last edited: Mar 6, 2011
  2. jcsd
  3. Mar 6, 2011 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi Help1212! :smile:

    (try using the X2 and X2 icons just above the Reply box :wink:)

    I assume you can find kx and kx2/2 ?

    ok, then k = … ? :wink:
     
  4. Mar 6, 2011 #3
    euhh... i'm still a little confused..how do i find k if I don't know x?
     
  5. Mar 6, 2011 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    x is twice kx2/2 divided by kx :wink:
     
  6. Mar 6, 2011 #5
    hmm. well when I move around the equation i get k=2[0.5(mv22)/x2

    from the assumption that K1 + U1 = K2 + U2

    Am i going in the right direction??
     
  7. Mar 6, 2011 #6

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    can you find kx and kx2/2 ?

    if so, what are they?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: Energy Conservation & Potential Energy Spring/Friction Problem
Loading...