I've noticed quite a few similar sorts of questions popping up about sensors, how they work, and I've noticed a few folks really have no idea about power management, all those little "non-Arduino" kinds of questions... Well these are questions we all have to learn!
I have a robot-based website that some folks might find helpful to try and understand some of the more mechanical and fundamental topics (gee, we have to know so much about so many things to do a robot correctly!).
The site is Rocky the Rover's home page!
The site is a little out of date regarding the newest sensors and specs, but hopefully the general ideas will be helpful to many folks. I've been in hospital on and off since my last update of the site, and Rocky's in a big box in the cupboard for now, but I'll try and put in some updates if anyone wants to know something specific.
I hope this helps, and gives some people some ideas! Questions, comments, or suggestions are most welcome!
Pete the Builder