Well, I'm a beginner, and i was reading the topic of Gravity and force here on stickpage
I read and ok... But, it tells a lot about PPF, I know what it means (Pixels per frame) but I can't find where to change PPF, Can somebody help me?

If helps, my pivot is 3.1

PPF is a term he uses to tell you to move it so many pixels more per frames, ie, you change it by moving the object. the difference in location by pixels from the last frame to the one you're on is the PPF for that frame.

Hum... got it, thanks Scorpioxxx

That helped a lot!