To find the magnitude of the normal force, you must express fn in terms of fw since ff is an unknown. using the equations you found in the two previous parts, find an expression for fn involving fw and θ but not ff.

You want to move a heavy box with mass 30.0 kg across a carpeted floor. you pull hard on one of the edges of the box at an angle 30∘ above the horizontal with a force of magnitude 240 n, causing the box to move horizontally. the force of friction between the moving box and the floor has magnitude 41.5 n . what is the box's acceleration just after it begins to move