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Homework Help: Physics: work

  1. Nov 21, 2004 #1
    anyone physic experts know how to do this questions?

    A force of 25 N parallel to a 35degrees inclined plane pulls a 2.5 kg block 5 m up the plane at
    constant speed.
    (a) How much work has been done by the 25 N force?
    (b) much work has been done by friction?
    (c) How much work has been done by the gravitational force?
  2. jcsd
  3. Nov 21, 2004 #2
    What have you done to try and solve the question? Where specifically are you have problems?
  4. Nov 21, 2004 #3


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    work=F(average)*(cos theta)*distance
    friction=coefficient of friction * Normal force
    gravity is always 9.80m/s^2 on earth
  5. Nov 21, 2004 #4
    this is what i got so far. W = F * distance

    so by the diagram I got:

    W = 25 N * 5m * cos 35

    but i know thats wrong... i dont' know how i incorporate teh mass
  6. Nov 21, 2004 #5


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    multiply the mass by gravity, but remember that gravity will be straight down and the normal force is perpendicular to the block, so use a net force diagram to sort out the remaining forces ... hope that helps, makes more sense in my head than it does typed, lol
  7. Nov 21, 2004 #6

    what part of the question are you refering to?
  8. Nov 21, 2004 #7
    for part a i got 102.4 J. does that look right?
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