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Need Help on Energy Homework! Please!

  1. Feb 15, 2012 #1
    1. Determine the distance it takes for a 25 kg box to stop sliding if it has a speed of 12m/s on a surface with a coefficient of friction of 0.15.

    2. W=F*d
    Coefficient of friction = Force of friction/Normal Force
    Kinetic energy = 1/2*m*v^2

    3. With the mass and the coefficient of friction, I got the force of friction.
    With the mass and velocity, I got the kinetic energy.
    Then I divided the Kinetic energy by the force of friction because the Newton's would cancel out and I would be left with meters.

    Is this the right solution? I checked the answer in the back and it is correct but I'm not sure if this was just a coincidence.
  2. jcsd
  3. Feb 15, 2012 #2
    The Kinetic Energy is equal to the work that the friction force must do to stop the box. Since W=Fd, the distance that box travels is d=W/F. So yes, you did it correctly.
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