What is the independent variable in my marble roller coaster?

I have to do a marble roller coaster for my 12th grade AP Physics class, and it says to have more than 2 independent variables.



What exactly do i change in a marble roller coaster made out of pipe insulation? The design, the

materials, the height the marble is released from?



Please help, I'm confused. ThanksWhat is the independent variable in my marble roller coaster?
The independent variables are the things which you control. They include the size of the marbles, the material the roller coaster is made of, the angle of the roller coaster relative to the table or the ground, the length of the roller coaster, and the height the marble is released from.



The dependent variable is how the marble responds in terms of how fast it moves and how far it travels.What is the independent variable in my marble roller coaster?
http://www.google.co.in/search?rlz=1C1GG鈥?/a>What is the independent variable in my marble roller coaster?
Things such as marble mass (this will effect speed and kinetic energy), height of release (this impacts potential energy), and length of roller coaster (this will impact friction loss). Have fun with it, do not be confused.