For my final semester exam, where building paper roller-coaster with marbles as the coaster and one of the things were testing is ride duration. The group with the longest run time will get extra credit and my GPA could really use the boost. so i guess my question is what's the best way to increase run time? the roller-coasters will have funnels, half pipes and a jump. I've already figured out that adding lots of funnels at the correct angle will increase my run time exponentially but my teacher warned me that another group has come up with a method using the tracks and funnels that will work so well that if i don't come up with something super cleaver there's no chance of beating them. so i figured i would ask people way smarter then myself who are actually super good at physics how they would do it. sorry for horrible grammar and punctuation, i wrote this in a hurry.