How to make a sphere fall from a cube when more than 50% of the sphere is outside the cube

I have a sphere that is moving on a cube. But when i reach the cube edges, it doesn't matter that more than 90% of the sphere is outside the cube, the sphere is not falling. How can i make my sphere to fall when >50% it outside the cube?

Image

Imagine that the cube is the roof of a building. So, in IMAGE 2 because of the gravity the ball should fall. In IMAGE 1, after changing the cube's size to X: 0.7, Y: 1, Z: 0.7 the ball is doing what i want it to do, but the visual effect is not very nice, the ball it's falling through the cube's texture.

So, how do i solve this problem?

No its not clear because you havn't said what is wrong or right in each picture nor have you explicitly expressed what you want to achieve. I've had to piece together exactly what you want over these lengthy posts which has proved impossible. Did you try what i suggested in the previous post? are you adjusting the collider size and not the actual size of the cube? all i can gather is that you want a ball to roll off a cube. I don't understand what the problem is?

I suggest start again, create a cube, adjust the scale of the cube in it's transform NOT the collider size in the collider component!!! Then create a sphere and add a rigidbody. I have just done it myself now and the physics are fine.

I suggest when asking a question make sure you clearly explain what you want to achieve, how you have tried to achieve it (what exactly you have done), and what precisely it's going wrong (and possibly why if you can figure that out)

reduce the size of the collision box on the cube so that the sphere appears to be inside the cube but is still actually rolling across the collider and therefor isn't actually inside.