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Homework Help: Can a car be considered in rotational equilibrium?

  1. May 18, 2008 #1
    The impression I'm getting of rotational equilibrium is that it applies to objects that are connected to an axis of rotation, such as a ball connected to a rod. What if a car was moving in a circular path, would the concept of torque apply to it, even though it's not connected physically to its axis of rotation?

    thank you!
  2. jcsd
  3. May 19, 2008 #2


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    Hi shortydeb,

    Rotational equilibrium exists when the total net torque on an object is zero. Static equilibrium is when the object is also not in motion. You can apply both concepts to a car (depending on the situation of course).

    You can definitely calculate the torque on a car. If a car is moving on a circular track at constant speed, what is the net torque on it?

    Did this answer your question?
  4. May 19, 2008 #3


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    Welcome to PF!

    Hi shortydeb! Welcome to PF! :smile:

    Rotational equilibrium is often used to calculate forces where there isn't really any sensible axis.

    For example, you may have noticed that if you and a friend are carrying a heavy pole, the one who holds it nearer the end supports less weight.

    This can only be calculated by using the fact that the pole is not rotating! :smile:
  5. May 21, 2008 #4
    I would guess it's zero since the car has no angular acceleration...

    anyway i thought about this for a little bit and i concluded (wrongfully or not) that any object can be in rotational equilibrium since the sum of the external torques just has to be equal to zero.

    Much appreciated btw.
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