1. The problem statement, all variables and given/known data A 1.6-kg block slides down a plane (inclined at 25° with the horizontal) at a constant speed of 2.0 m/s. At what rate is the frictional force doing work on the block? 2. Relevant equations 3. The attempt at a solution I think that you have to find the potential energy, kinetic energy, 1/2mv^2 , and the force acting on the block, f =m* g. then subtracting the potential from the kinetic and force and this should give me the frictional force acting on the block, right?