# Can a car be considered in rotational equilibrium?

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!

alphysicist
Homework Helper
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?

tiny-tim
Homework Helper
Welcome to PF!

Hi shortydeb! Welcome to PF! 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! 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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