So at school we had to make our own experiment, and we tried to make a loop-the-loop. We let a marble go from some height. But now we've got a problem. We had a sensor on the top of the loop, to see how long it does to go to the top of the loop. But it didn't make sense. So I had to fake the results(the time) I need to know what the connection is between the height and the time it'll arive at the top. Edit: This is our set-up: http://imagizer.imageshack.us/v2/xq90/34/iqqk.jpg [Broken] We just simply put a light sensor at the top of the loop, if the marble goes through the top the light sensor will notice a drop in voltage. So we'll know at which time i'll reach the top. This is between 0,20 and 0,40 seconds. But, the connection between the total distance (or speed) and the time doesn't make sense if we use our real results. Could you explain to me what the connection is between the the total distance ( or speed) and time? Like lineair. That would be really great. 1. The problem statement, all variables and given/known data Diamater of the loop-the-loop:29m Height values are: 0,30 0,32 0,53 0,57 0,60 0,64 0,68 0,70 0,74 0,77 0,82 0,87 2. Relevant equations What is the link between the height and the time it will arive at the top? 3. The attempt at a solution I've tried to make a diagram, but it's weird. I also tried to fake the results (the time), but with no avail. I have to know what the connection is of the height and time it will arive at the top. It gave me a real headache Ty for your time, and sorry for my bad english.