Prоblem instructiоns: As yоu work through this problem, write down your work аnd the steps leаding to your аnswer. Once you arrive at an answer and have written down your work, click on your preferred choice below. Then, show your work to your external camera (such that it can be clearly viewed and read) and then additionally explain your work and reasoning aloud (speaking to your external/microphone) as you would explain it to an instructor. At the end of the exam, after completing all problems, you will upload your written work to the "exam upload repository" in short order (to be uploaded in a short but reasonable time span, within approximately 10 minutes of completing the exam). A set of legible camera photos of the written work will suffice. The velocity of a particle moving purely in the vertical direction (z) is given by