Bullet speed and physics!

Questions & Answers
1

Does the physics engine in Unity has the ability to calculate the collisions for a bullet with a speed more then 3000 pixels per second?!

2

Probably not, there are many issues with fast moving objects and collisions. But there are also workarounds, using Raycasts. Depends on what level of realism you are aiming for. There are many discussions on this topic, for example this one.