This seems like an old blog
but I would propose that in equilibrium all bodies (black or gray) in a constant radiation flux would reach the same temperature
The black ones heat and cool at the highest possible rate, and the gray ones heat and cool at a lower rate, but the emissivity is on both...
There is this experiment my high school teacher showed in physics class. You are probably aware of it
(from practicalphysics.org)
There is a video of a teacher actually doing the experiment here:
https://sites.google.com/site/haatscience/physics/221-the-effect-of-inertia
Gradually pull the...