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Homework Help: Physics Question Regarding Impluse, Momentum, and Velocity.

  1. Dec 8, 2008 #1
    I'm not sure exactly sure how to set up this problem...

    1. The problem statement, all variables and given/known data
    A hockey puck with a mass of 0.160 kg is at rest at the origin (x=0) on a horizontal, frictionless surface at time t=0, a force of 0.250 N is applied to the puck parallel to the X axis, the force is applied until time = 2.00s.

    2. Relevant equations
    What is the acceleration, position, and speed of the puck at t=2.00 s

    3. The attempt at a solution

    Impulse (J) = (F) * (∆T)
    J = (0.250N)*(2.00s)
    J = .5 NS

    I know J = ∆ Momentum (P) ; and P = Mass * Velocity, but i'm not exactly sure how to calculate what it wants me to find.

    Any help will be appreciated.


  2. jcsd
  3. Dec 8, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    You have the force. What does that tell you about the acceleration?
    You found the impulse. What does that tell you about the speed at t=2.00s?
    Use a little kinematics to find the distance traveled.
  4. Dec 8, 2008 #3
    I think i get it but aren't completly sure

    so using P=mv
    .5 NS = 0.160 kg * v

    v= 3.125 m/s ?

    A = (3.125 m/s) / 2.00s
    A = 1.563 m/s^2

    and position:
    X(final) = X(initial) + V(i)t + 1/2 at^2
    X = 1/2 * (1.563 m/s) * (2.00s)^2
    X = 3.125m

    Could someone confirm that is correct please?
  5. Dec 8, 2008 #4

    Doc Al

    User Avatar

    Staff: Mentor

    All good!
  6. Dec 8, 2008 #5
    wow that was alot easier than i thought. Thanks for your help.
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