1. The problem statement, all variables and given/known data Hey, Basically my EPI (Extended Practical Investigation) is coming up and I need to conduct an experiment in class and research at home. The topic is Motion, and I can pretty much do anything I want - as long as i can work something out, or prove a formula. I was initially thinking of doing proving the Drag Coefficient of a balloon, but to do that, I would essentially need the terminal velocity of the balloon to work out the Drag Coefficient - which I can't do effectively. What i mean, for example, is ie - Taking 5 springs that are identical. Use one spring to calculate the K constant for those springs. Then, join the springs in parallel AND in series to work out if the K constant changes when they work together, and try and establish a relationship. That's just an example for you guys to see what i'm trying to say, basically just wondering if anyone here has any ideas on what type of topic to do for the Prac / Experiment. I will be extremely greatful for any help or ideas in regards to what to test or experiment on!