you're helping with an experiment in which a vertical cylinder will rotate about its axis by a very small angle. you need to devise a way to measure this angle. you decide to use what is called an optical lever. You begin by mounting a small mirror on top of the cylinder. a laser 5 m away shoots a laser beam at the mirror. Before the experiment starts, the mirror is adjusted to reflect the laser beam directly back to the laser. later you measure that the reflected laser beam, when it returns to the laser, has been deflected sideways by 2mm. How many degrees has the cylinder rotated?