I have been struggling through my physics class this summer (it doesn't help that 5 months worth of material is crammed into 2 months in an online classroom). This site has helped me out a lot, but I am still stumbling through understanding when to use certain equations. When I started reading the book, it would give an equation, and then suddenly it would say to use another equation to solve a problem because you plug the first equation into a second equation to get a third equation. It baffled me. If I understood when to use certain equations, I think I would do a lot better. Is there a simplified chart or tutorial that can help me understand all of these equations better? On a side note, I don't understand when to use m/s vs. m/s^2. Any tips?