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Banked turns; do we use the x component of normal force or gravity?

  1. Sep 16, 2013 #1
    I am confused on what the correct way to do this is.

    In my old physics textbooks, they say that the x component of gravity is responsible for the centripetal force.

    However, on the internet and for more advanced topics they say it is the x component of normal force that is responsible for the centripetal force.

    Analyzing this myself, it seems like it does not matter which method is used, as long as you pick a specific viewpoint and stick to it.

    Does this hold true? Or is one of them more correct than the other? Thanks.
  2. jcsd
  3. Sep 16, 2013 #2
    It depends on your frame of reference. In a frame of reference with a vertical y-axis, gravity is vertical and has no x component, while the road is not horizontal, so the normal force has an x component.

    In a frame of reference with an y axis normal to the road, the normal force doesn't have an x component, but gravity does
  4. Sep 16, 2013 #3
    Ah, thank you for clearing this up. It is what I thought.

    EDIT: Just to add another question. If the normal force is the Y axis, then gravities X component seems to align perfectly with the road, directly parallel

    However, if gravity is the Y axis then it doesnt seem like the normal forces X component is perfectly parallel to the road.

    Wouldnt something like that matter?
    Last edited: Sep 16, 2013
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