Nvidia offering its real-time physics engine Physx SDK for free to registered PS3 developers.
In Physic term:
Physx is generates real-time physics in games by calculating the trajectory of objects, their angle of collision and their impact force.
In Simple term:
Physx provide more easier and give the game more real.
It have been using on many games platform such as PlayStation 3, Xbox 360 and Wii.
The main competition in Physx for Nvidia is Havok Physics, a software company from Irish.