Hi, I was reading a physics book and started to make some links, but i don't know if it's correct. For example: I need to calculate the power to move a car in a slide with friction. But as far as it's a car pulled by an motor, the motor provides the needes force to keep the speed. I made the relations using moment: Work = Moment and Work = Energy M = F x wheel radius (this relation is between moment, pulling force and wheel radius of the car) K = 1/2 m x v^2 Friction = m x μ x cos α Horizontal component of weight: Px = m x sen α So, I applied the forces (friction, horizontal component of weight and resultant force) in the wheel radius: wheel radius x F - Friction x wheel radius - Px x radius = 1/2 x m x v^2 With this I found the force W = F x d but I need to convert to [Newtons] P = W/t I would like to know if this relations are correct. As far as it isn't a conservative system, I got a bit lost. I tried to get some numeric examples from the books to clarify, but I didn't find any example close to this. Only hypothetical systems that don't fit to reality. What about the potencial energy, should I take in consider too? Thank you very much!