applying "spin" to a flicked coin

I’m half-working on a game where you flick coins across a green felt table and they knock into others, kind of like billiards would be in Flatland.

There’s no “game” implemented yet but the mechanics all work, except I’m not mathed enough to figure out what kind of angular velocity to apply to the coins so they would realistically spin (slightly) as they ricochet off of the sides and other coins.

Any thoughts on what the equation could be to implement this? I’ve played with the code and can get the physics body to spin (manually) and match that same rotation on the coin sprite that is covering the body, but that’s all done manually. I’m lost mathematically as to how to make it happy organically.

In principle, you should measure the finger speed vector V when he leaves the coin after pushing it.
Then project it on the tangent to the circle at that contact point, to get tangential speed Vt.
Then the rotation speed is w = Len(Vt) / radius / deltaTime, in Radian per second.