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Homework Help: Sorry for Double Post but I need Help Please

  1. Nov 9, 2004 #1
    Sorry for the double post, but this edit wasnt showing up for me on other post, so i post it here.

    I also came across another challenging problem, devising of an equation for Acceleration on an inclined plane.

    Q: A toy car is released from rest at the top of a ramp going down to the right. Assuming that friction IS present derive an equation that could determine the acceleration of the car.

    SFy - sum of forces in the y direction
    SFx - sum of forces in the x direction
    Fn - Force Natural
    Fgy - Force Gravity in the Y-direction
    Fgx - Force Gravity in the X direction
    m - Mass
    a - Acceleration
    U - Coefficient of Friction
    Fg - Force of Gracity
    Ff - Force of Friction

    Here is my work, though I think i went wrong with the sin and cos values

    SFy = Fn - Fgy = 0
    Fn = Fgy
    Fn = cos(Theta)Fg
    SFx = Fgx - Ff = ma
    SFx = Fgx - FnU = ma
    SFx = Fgx = ma + FnU
    SFx = sin(Theta)Fg = ma +cos(Theta)Fg
    SFx = sin(Theta)Fg / cos(Theta)Fg = ma + U
    SFx = tan(Theta) = ma + U
    SFx = tan(Theta) - U = ma
    SFx = [tan(Theta) - U] / m = a

    Once again help would be appreciated..thankz for all help and corrections
     
  2. jcsd
  3. Nov 10, 2004 #2
    Okay, I'm not going to use those variables because it's too comfusing

    First, a=net force/mass
    U - Coefficient of Friction
    Force of Friction=UmgcosX
    Force of the car=mgcosX

    Net Force=mgcosX-UmgcosX

    a=net force/mass
    a=(mgcosX-UmgcosX)/m
    a=gcosX-UgcosX
     
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