Ok, well thanks for all peoples help. I think I will assume terminal velocity has been reached so drag is constant. However, the terminal velocity will change and this will simply be the last 2m of the fall divided by the time it takes to fall these last 2m. I will now change my independent variable to the radius of the CONE but will keep the original radius of the flat CIRCLE I cut out the same. Going back to the OP now. I have two questions:Ohhh, I think I get it now. All of the accelerations and velocity are completely useless, since in the end we are looking at terminal velocity regardless of time and which reaches the ground first. Am i right?
I think you should carry ahead with any independent variable, execute the experiment and hope that your independent variable had an effect. If not, then try and look at your equations and see why. Go ahead with the experiment, if anything doesn't go perfectly, you can just find the problem and explain this in whatever you might submit to your teacher. There's no harm in being wrong or not getting the results you expected.
1) The drag equation shows that cross-sectional area is inversely proportional to the square of the velocity (if everything else is held constant). Should I get a graph of y = 1/x2 if I plot terminal velocity against base area of cone. I only ask because the base area is not exactly the same as the cross-sectinoal area in contact with the air since the cone is dropping with its point facing down. Is there a simple mathematical way to relate base area of the cone to velocity (if it is not inversely proportional to the square of the velocity)?
2) At terminal velocity, will the drag coefficient Cd be a constant (as it needs to be if my independent variable is base area of cone and dependent variable is terminal velocity)