Ideas For Moving Toy Project How To Find Out How Much Pipe Is Needed?

How to find out how much pipe is needed? - ideas for moving toy project

I'll try a science project in school and understand, such as pipe, I take a golf ball a little toy car need. The idea is that the golf ball in the tube, then a level of elbow 45 1 inch. After his departure, the little toy car and the car will be affected to a speed high enough to go to another golf ball Oasis pads. 2 feet of the pipe is too much, he jumps directly to the car. If you have only one elbow, then just bump the car, and have not fast enough to hit the golf ball ramp. Why can not I just jumped on the car? I have to use up to 6 steps (This is a Rube Goldberg project) to move a box of aluminum, and the car is one of my 6 steps. No idea how to measure the correct amount of pipe gor fast enough?