An object moves in the xy plane in Figure P7.43 and experiences a friction force with constant magnitude N, always acting in the direction opposite the object’s velocity. Calculate the work that you must do to slide the object at constant speed against the friction force as the object moves along (a) the purple path O to A followed by a return purple path to O, (b) the purple path O to C followed by a return blue path to O, and (c) the blue path O to C followed by a return blue path to O. (d) Each of your three answers should be nonzero. What is the significance of this observation where x = m ?