Q: The directions say to attach the rollercoaster to the 5 th hole from the bottom. However, I want to raise and lower the track to demonstrate different potential energies. What should I do?
A: This track was engineered to attach to the 5 th hole from the bottom. This is so the marble hugs the track for the entire trip, and does not become airborne at all. This insures that the exact diameter of the marble passes through the beam, and the speed calculations will be valid. If you want to demonstrate what happens to the marble when you raise and lower the track, go right ahead! Just please do not trust any photogate data unless the track is in the 5 th hole from the bottom.
Q: Can I use different types of marbles on the track? I would like to try larger and smaller marbles.
A: For photogate data to be valid, the marble's diameter must pass through the beam. The track is engineered to work with 1.9 cm diameter marbles. If you use other sizes, please do not trust any of the photogate data!
Q: The times I get for the marble to pass through the photogate are very consistent when I run several trials without moving the photogate. HOWEVER, when I try this at the very top of the second hill, the times vary greatly. Why is this happening?
A: The marble is moving very slowly at the top of the second hill. This is the place where the greatest variation in speed occurs, and this is the place where you will see the greatest variation in time data. Try multiple trials at any other spot on the track, and your results will be consistent, often within one or two ten-thousandth of a second!