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Sliding hammer leaves the roof

  1. Mar 8, 2009 #1
    Good morning, first post and more than excited that I can get possible help for physics. Only problem I think I have is translating physics problems into soluble questions.

    1. The problem statement, all variables and given/known data

    A hammer slides 2.5 m down a smooth roof which has an incline of 15 degrees.

    At the instant the hammer leaves the roof, find the magnitude Vo and direction of the angle of its velocity.

    x = 2.5 m
    angle = 15 degrees

    2. Relevant equations

    X = Xo + Vot + 1/2at^2
    V^2 = Vo^2 + 2a(X-Xo)
    X = Xo + 1/2(V+Vo)t

    3. The attempt at a solution

    Having two unknowns is leaving me at a halt. Is final velocity [at the instant leaving the roof] 0 m/s? The last equation [X = Xo + 1/2(V+Vo)t] would have V = 0 m/s and Vo = 0 m/s making the entire equation unsolvable.
    Last edited: Mar 8, 2009
  2. jcsd
  3. Mar 8, 2009 #2


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    Homework Helper

    Welcome to PF.

    You only need to determine your Vo. It is accelerated over the distance of the roof by what part of gravity? (You have the angle so figure the component of gravity that accelerated it.)

    Doesn't look like you need your kinematic equations.
  4. Mar 8, 2009 #3
    I used the equation

    V^2 = Vo^2 +2a(X-Xo)

    and through algebra got

    Vo = square root of 2g(X-Xo)

    my question is should we reconstruct the the equation to be Vo = 2gcos15(X-Xo) in respect to the incline?

    Editnm i got it! Thanks alot! =]]]
    Last edited: Mar 8, 2009
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