# Example of anisotropy frame of reference

I have studied that an inertial frame of reference is the one that is homogeneous, isotropic and time-independent.

For instance, a reference frame on a rotating wheel is not an inertial frame of reference because it is not homogenous (depending on where we are, the body feels different inertial forces acting on them).

Could you provide me a similar example of a reference frame that is not isotropic?

The surface of the earth (locally), or similarly, an elevator accelerating "up" at $$g$$ is not isotropic. There is a preferred direction, down, defined by $$\vec g$$. In this frame, angular momentum is not conserved. For example: the classic simple pendulum has an oscillating angular momentum.