"Waves" in Tennis

After a tennis lesson on Friday, I realized that the quickness drill I had to do has a lot to do with Physics. As shown in the picture above, the drill I did involved moving laterally (side to side). I had to start in the middle of the service box and go side to side from the middle line to the alley line. It seemed like I was moving in simple harmonic motion because each time I go from one line to the middle, I complete the amplitude of my motion and I do it again when I go to the next line because I’m moving the same distance each time. My speed doesn’t change much either, so it can be considered simple harmonic motion. My coach made me keep doing this drill until I was able to touch 22 lines in 30 seconds. That made me think about the period I had to complete to go from the middle to one line, to the other line, and then back to the first line. I would have to move the equivalent of 10.5 waves in 30 seconds, so the period of one “wave” would have to be about 2.86 seconds. On my first and second trials I only touched 21 and 20 lines, but on my last trial, I touched 22 lines and reached the goal of having a period of 2.86 seconds.