Physics Help

Caitlin has been sick with a fever all week. So Eric has been trying to tutor her over the phone with pictures and texts. This is what he wrote up for her yesterday with a paper towel and Sharpie marker before he had to rush out to work. I laughed. Who can read or understand this? At least he is trying. Eric just "gets" math and science and he doesn't have much patience for those of us that do not.