1. The problem statement, all variables and given/known data A case is being pulled along horizontal ground by means of a rope. Show that the force required to keep the case moving at constant velocity along the ground is a minimum when the rope is at an angle θ to the horizontal, where: tanθ=[itex]\mu[/itex]k 2. Relevant equations F=ma FF=[itex]\mu[/itex]kN 3. The attempt at a solution So I drew out the free body diagram and got my forces in the x and y directions. For the x-direction I got: FF-Fx = ma For the y-direction I got: N-W+FY=0 I then got the N values on their own and equated the equations but couldn't really get anywhere with it. Any help that could put me in the right direction would be greatly appreciated.