It's been a while since I've done any work-energy questions, and I just noticed how vague some questions could be (or maybe I don't understand it that well). Anyway, suppose I have a box moving down an incline where the only forces acting on it are its weight, the normal force, and friction. Now, can I assume that this box is moving in constant velocity, or there is zero net force? Or is this something that is apparent and it does not need to be assumed since in this particular question the assumption was never given, but the known variables seem fit the case where there is constant velocity. Thanks.