Roller Coaster Marbles Question.

[imkevinxd]

Hello,

I am doing my science fair project on the "Roller Coaster Marbles: Converting Potential Energy to Kinetic Energy." I have a few questions about the procedure: https://www.sciencebuddies.org/science- ... M&from=TSW

Procedure 5A states that "In order to measure the velocity of the marble, you'll need a way to measure how much distance the marble travels during a measured time interval. A good way to do this is to interrupt the foam track and direct the marble along a smooth, level surface (e.g., two long pieces of Masonite glued in a V-shape). Support the Masonite V (with cardboard, beanbags, etc.) so that it is level with the end of the foam track."

By "interrupting" the foam track, does it mean that I put the Masonite V on the foam track or what? Is it supposed go with the track the whole way? Where would I put the Masonite V if I also add a loop to the foam track? Do I put it at different points of the track?

My last question is that am I supposed to compare the marble's initial gravitational potential energy to the velocity of the marble during the whole track or what?

I know this is a high school level project, and I am an 8th grader, but I really want to do this one because I did the other roller coaster marble project in 6th grade.

Thanks in advance!

[deleted-71588]

By "interrupting" the foam track, does it mean that I put the Masonite V on the foam track or what?

My interpretation is that you "cut" the foam track at some point where you want to measure the velocity and insert the Masonite V between the two pieces of track such that a marble rolls off the previous foam track and onto the level masonite V and then onto the subsequent foam track without changing height or direction. In other words, the masonite V needs to approximate a frictionless level surface so that no significant forces on the marble occur during that time it travels that section so that its velocity is not changing significantly on that section. This allows you to measure the time of transit over the masonite V distance to determine an accurate approximation of the velocity at that point of the track.

Do I put it at different points of the track?

You need to use a level Masonite V track section every place you want to measure velocity using this method. Where you need to measure the velocity should be determined by what you are attempting to prove. Without knowing your hypothesis and the specifics of your test track, I don't have enough information to make any recommendations other than to state that trying to measure velocity with this method in a loop or other track configuration sections where centrifugal forces exist is not feasible.

You might want to consider using a stationary video camera and some means of analyzing the recording frame by frame to measure time and distance so you aren't restricted to inserting straight level track sections for velocity measurement.

[imkevinxd]

Thank you very much, Craig. You cleared up a lot of things up for me.