An Observer In A Pickup Truck Is Watching A Model Rocket Ascend The Pickup Is 0

I have attached my question. This question does have quite a few steps so I will make sure there is plenty of time for the time limit. I have tried working on some of the steps but I have been stuck on a majority fo the parts for awhile. Your help is very much appreciated! (: I also saved the file as a Rich Text Format, if you can’t view it then let me know and I will save it as something else!