Hello, I am taking a fluid mechanics class right now, so I deal a lot with water flowing through a pipe, and equations involving the density of the fluid. The problem is, that since I'm an engineering major, we use way too many english units. There is something inherent about non-SI units I believe that makes my calculations hard to follow, especially when dealing with the density of a fluid. The book will randomly divide the density by the gravitational constant, and I am having trouble understanding why the gravitational constant is omitted sometimes and not omitted other times when doing calculations, and how I can keep it straight when to include or not include it. For example, the equation p = ρgh. You end up dividing out the constant g. Also, a kg m/s^2 is one Newton. Is a lb_m ft/s^2 a lb_f??