A box of weight w=2. 0n accelerates down a rough plane that is inclined at an angle ϕ=30∘ above the horizontal, as shown (figure 6). The normal force acting on the box has a magnitude n=1. 7n, the coefficient of kinetic friction between the box and the plane is μk=0. 30, and the displacement d⃗ of the box is 1. 8 m down the inclined plane.