Cube balanced at equilibrium about two different axes

[eprparadox]

Homework Statement

A cube balanced with one edge in contact with a table top and with its center of gravity directly above the edge is in _______ equilibrium with respect to rotation about the edge and in _________ equilibrium with respect to rotation about a horizontal axis that is perpendicular to the edge.

A. stable, stable
B. stable, unstable
C. unstable, stable
D. unstable, unstable
E. unstable, neutral

Homework Equations

The Attempt at a Solution

I know the answer is C.

So it's clear to me that the first one is unstable.

And maybe I'm overthinking this but for the second option, I can't seem to put in my head why it's stable. Do we just imagine that it's fixed on its edge and rotating about the horizontal axis?

And more importantly, what would it look like for the cube to be in unstable equilibrium relative to the horizontal axis.

 

[haruspex]

Do we just imagine that it's fixed on its edge and rotating about the horizontal axis?

Both axes are horizontal. Do you mean the perpendicular axis?
It is stable about the perpendicular axis because a modest torque applied about such an axis will have no affect.

what would it look like for the cube to be in unstable equilibrium relative to the horizontal axis.

Unstable about all horizontal axes? Balanced on a point.

 

[eprparadox]

Awesome, this makes a lot of sense. Thanks so much