Box collider fell "inside" into another one (Collision)

I’ve the following environment:

  1. Floor -- it is a cube scale by (10, 0.2, 10). Box Collider Material = wood
  2. Tiny Box -- it is a cube scale by (0.02, 0.05, 0.01). Box Collider Material = wood. I added RigidBody
  3. The tiny box is on top of the floor
  4. Apply rigidbody.AddForce(90, 0, 0) to the tiny box. The tiny box falls down as expected.

However, about half of the tiny box body fell “inside” the floor. I was expecting the tiny box is (fully) on top of the floor.

What did I do wrong?

Thanks in advance for your help.

I’ve just found out this discussion Collision - Issues of Scale…

Per suggestions on the above discussion, I did the following:

  1. Go to **Edit > Project Settings > Physics**
  2. Change the **Min Penetration For Penalty** from 0.01 to 0.001

It seems that it solves my problem.

Here go go, enjoy:

Honestly, I found this is just a natural function of Unity’s physics that I try my best to cover up. On the floor change the collision detection in the rigidbody to “Continuous” and the one in the box to “Dynamic Continuous.” This probably won’t do much. You can also just scale the whole scene up, I’ve found that helps, and adding mass to the floor. I don’t really know, as I too am starting in Unity so there may be a solution I don’t know about.