A leftward force of 7N is applied to a box while the force of friction is 3N. The weight of the box is 4N as is the normal force. Determine the net force, and its direction acting on the box. (Hint: draw a free body diagram to help you figure it out)

Light from two different sources are incident upon the same side of a polarizing filter. light from one source is polarized with total intensity ip, while light from the other source is unpolarized with total intensity iu. as you rotate the polarizing filter through 360 degrees, the intensity of the transmitted light on the other side varies by a factor of 9. what is the relative intensity of the initial polarized source to the unpolarized source, or ip/iu?