Irrlicht Engine

Is best use 'pure' Newton, IrrNewt or IPhysic?

why?

in my opinion newton is the best physics engine for beginers, maybe even for advanced users. i suggest you to use pure newton because you will learn more about it. using frameworks makes life easyer but cuts off part of knowledge. im beginer myself and i easily implemented newton to my project just using manual from the site. just be aware - manual is buggy. better download example project and study source files

The answer also depends on your licence requirements. Links and brief notes on the engines can be found in the Irrlicht Wiki.