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Homework Help: Help on a Physics Problem

  1. Mar 24, 2005 #1
    A supertruck is fighting its way up an steep 65 degree incline with an acceleration of 3.3 m/s^2. If the truck has a mass=1.00 tonne and an engine applied force of 1.55 X 10^4 Newtons, find the co-efficient of friction.

    1 tonne = 1000 kg

    **I got 0.80 as my answer....can anyone confirm this?
    Last edited: Mar 25, 2005
  2. jcsd
  3. Mar 24, 2005 #2
    Find the magnitude of gravity down the slope
    Find the ideal acceleration of the truck by dividing force and mass.
    Find a net force from the above two forces.
    Find a net acceleration from this net force. (Divide by mass)
    Compare this net acceleration to the acceleration provided.
    Find the friction force by subtracting the two forces.
    Divide by the normal force to get coefficient of friction.
    Normal force is [tex]mgcos(\vartheta)[/tex]
  4. Mar 25, 2005 #3
    Thank you....is 0.801 the answer?
  5. Mar 25, 2005 #4
    Resultant force = ma

    let friction = F.

    so, resolving forces parallel to the slope, using g=9.81N/kg:
    F = ma
    1.55*10^4 - F - 1000gcos65 = 1000*3.3
    F= 8054 N

    F=uR, where u = coefficient of friction
    u = F/R
    u = 8054/(1000*9.81)
    u = 0.82
    Last edited: Mar 25, 2005
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