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Homework Help: Conservation of Energy (Spring + Kinetic)

  1. Nov 20, 2005 #1

    IB

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    Tonight I've got so many hard problems...

    A 3.0 kg mass slides across a frictionless surface and collides against a spring bumper with a velocity of 3.0 m/s as shown in the diagram. Determine the maximum amount of the spring compresses if it spring constant is 335 N/m.

    For this one I don't know whether I should use E_kin = E_spring then solve from there or E_kin(i) + E_spring(i) = E_kin(f) + E_spring(f), but as for the former I got:

    1/2 mv^2 = 1/2 k (delta) l^2
    mv^2 = k(delta) l^2
    (3)(3)^2 = (335) (l^2)
    x = .081 m

    Is that right? Thanks a lot for your help so far, everyone! I really appreciate your time and kindness. :smile:
     
  2. jcsd
  3. Nov 20, 2005 #2
    looks good.

    except the spring epe is .5kx^2
     
  4. Nov 20, 2005 #3

    dx

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    Homework Helper
    Gold Member

    Both the equations are valid. The second one reduces to the first one since E_spring(i) is zero and E_kin(f) is zero.
     
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