Hello, I have this Physics problem that's due tomorrow in class and I'm having some troubles with it. 1. The problem statement, all variables and given/known data PROBLEM: A racing car has a mass of 1500kg is accelerating at 5.0m/s^2, is experiencing a life force of 600N up (due to its streamlined shape) and group effects of 1000N down (due to air dams and spoilers). Find the driving force needed to keep the car going given that "u" (micro) = 1.0 for the car. 2. Relevant equations This is where the problem is. I always get confused and have no idea what formula to use where. To be honest, I'm not sure what I am supposed to find. Fn, Ffr, Fg or Fa. Are there any tips that people have or suggestions on how to determine what formula I need? Also, I get confused on what is what in a question. Like, if it's Fa or Fg or what Ffr. Some formulas that I do know which I used: W = mg Fa - Ffr = ma Ff = "u"W 3. The attempt at a solution Regardless of that, I still tried the question. I did get an answer but I would like it if you guys could explain the whole thing. And, not just numbers. I actually want to know why I subtracted 1000N - 600N = 400N and added it to the 22000N. Heres my work: http://img262.imageshack.us/img262/3125/scanhe3.jpg [Broken] Also, I wanted to know if there were any forces tutorials anyone knows about. It'd be really nice if they were video lectures but anything is appreciated since I have a test coming up on it soon. Thanks for all your assistance. Prim3.