I originally wanted to post this in the EE forum, but after seeing the sticky there, I decided that this might be a better place. 1. I got the whole thing about unit conversions (like from V to kV, move the decimal point 3 to the left -- the number becomes smaller by 10^3). Right now, we're at Classical Mechanics (motion, kinematics, static etc.) and I don't know how to convert composed units. Like how do I convert from m/s to km/h, or backwards from km/h to m/s. A step-by-step explanation would be most appreciated. 2. I took up Electricity on my own, kind of a hobby, and I started studying the text book. So far, just the first chapter, brushed up on some old concepts. There are a few things I don't quite get though. Energy (joules), power (watts). What they really mean, why P = E * I, and all of that. Could anyone shed some light on this?