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Inclined Plane

  1. Jan 6, 2014 #1
    This is driving me nuts. What am I missing?

    Suppose you have an inclined plane with a mass m resting on it. The free body diagram for the mass m has F_grav downward and F_normal perpendicular to the surface of the inclined plane. Thus, by Newton's Second Law, you have:

    F=F_grav+F_norm=ma with the bolded script indicating vectors. Because F_normal=F_grav*cos(α) where α is the angle of the plane's inclination you get


    But this doesn't make any sense! This indicates that, as the inclination of the plane gets lower and lower, the acceleration gets higher. It's obviously a wrong result but I can't, for the life of me, figure out where my mistake is. lol Any help would be greatly appreciated.
  2. jcsd
  3. Jan 6, 2014 #2


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    hi rexregisanimi! :smile:
    nooo :redface:

    they're not parallel, are they? :biggrin:
  4. Jan 6, 2014 #3
    Ah yes. lol Thanks :)
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