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Homework Help: The fuel level inside a tank.

  1. Dec 23, 2012 #1

    I do not know how to solve this problem. I need some help.

    How would we find out A, the angle between the horizontal and the fuel level line inside the tank of a car?.

    The car speed does not change, let´s say 60 km/hr, but we are driving in a roundabout. So, the fuel inside the tank will be displaced to the right due to the centrifugal force (in England it will go to the left). Lets imagine that car body is horizontal and not affected by the curve. (see attached pic).

    We know the car speed and the radius of the car turn. Can we determine angle A?. Will it depend on how much the tank is filled ? any other variable ?

    Thank you very much in advance and Merry Christmas.

    Attached Files:

  2. jcsd
  3. Dec 23, 2012 #2


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    Staff: Mentor

    Can you solve the problem if the car moves in a straight line, but with acceleration?
    It is the same in the roundabout, just the direction of the acceleration is different (you can assume that the whole fuel tank has nearly the same distance to the curve center - otherwise the surface would be a bit curved). Can you calculate the acceleration of the car in a roundabout?
  4. Dec 23, 2012 #3
    Hello mfp and thanks for replying,

    Yes, I can solve the acceleration of the car in the roundabout as a function of angular velocity and curve radius but I wonder how the liquid is displaced.

    I assumed that in the case of having an centripetal acceleration same as the gravity the fuel level and the horizontal angle will be 45 degrees. But this is not the case and that is why I am asking for way of determinining that angle as a function of, angular velocity and curve radius.

    Thank you.
  5. Dec 23, 2012 #4
    I happen this: A= arctan (ω2*r/g)

    being ω the car angular velocity
    r the curve radius
    and g 9.8 m/s2

    but it looks too simple to be true.

    Last edited: Dec 23, 2012
  6. Dec 23, 2012 #5


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    Staff: Mentor

    Why do you expect something more complicated? ;)
    It is right.
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