Banked curve curcular motion

  1. hello good morning. Let look at the two diagram.
    (back view)

    In STATIC, a car is remauning static at a bank curve and its force diagram is as follows. for this case, the normal force is smaller than the weight of the car and friction exists in the directiin perpendicular to car.

    In MOTION, the car is moving into the screen and is surrounding a banked curve. now what i am so surprised with is that THE MECHANISM OF FORCE CHANGING. if we inspect a car changes it state from.diagram 1 to 2, we wil actually realize that the normal force gradually increases until its vertical component Ncos(∠) is equal to the mg and balances the weight of the car. meanwhile there is an unbalanced component that causes centripetal force ,Nsin(∠) . Can anyone explain to me the actual mechanism of this changes in normal force?? or correct me if i am wrong.
     

    Attached Files:

  2. jcsd
  3. Simon Bridge

    Simon Bridge 15,053
    Science Advisor
    Homework Helper
    Gold Member

    Why did you not include the friction force in the "motion" diagram?

    You mean you start with the car stationary on a banked curve and then it accelerates around the curve?
    In order to accelerate the car must experience a net unbalanced force. The mechanism for this is the wheels contact with the ground. As it accelerates around the corner, it will have an increasing centripetal component - which comes from the reaction from the ground ... so the normal force must increase.

    The mechanism is that the car has to push against the ground in order to change direction and the ground is fixed in place so it must push back - just the same as the normal force knows exactly how hard to push on the car in the stationary case.

    Another way to think about this is to consider what would happen if the ground did not push hard enough against the car to make it turn.
     
    Last edited: Apr 9, 2013
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