Science Buddies: "Ask an Expert"

Hi,

I am helping my son build the roller coaster for his science project: Roller Coaster Marbles: Converting Potential Energy to Kinetic Energy

At one point, it says: "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."

I am really having difficulty visualizing the V-shaped masonite. Does anyone have a picture of that? I understand inserting a length of masonite to measure speed over distance covered, but what is the V-shape part? How does it come into the picture?

Thanks in advance.

Hi majouz,

That is a really neat project and I hope that it is going well for you. The idea of the masonite is that you have control over how long this portion of the track is, so you can measure it fairly precisely. To construct this, imagine taking two rectangular (relatively thin compared to the length) pieces of masonite. Lay one flat on a table top and take the other and place it on top so that they line up. If you now pick up the top piece so that the shorter edge (keeping the lengths the same) is touching and line up the outside edges, you will have a L shape on the table. If you rotate this so the point of the L touches the table, then it will make a V shape instead. This is you guide rail for the marble. The idea of using the masonite is that it is relatively smooth so it won't slow down the marble very much. This way, you will get a more accurate measure of the speed of the marble.

Hope this helps and best of luck!

mjacobsen