Science Buddies: "Ask an Expert"

Hello Scientists,
I have a couple of questions on this science project, The Science of Spin: A Baseball Pendulum Advanced Medium.
For my first question, the grid were supposed to make out of cardboard, what are the dimensions of the grid? Also do we hang the pendulum on something or hold it with our hand?
My next question is, I am interested in this project, I want to incorporate different pitches into this project? How can I make these different pitches relate to this pendulum project of how pitchers throw different pitches and how can I replicate the spins of these pitches; fastball, knuckle, etc?
Thanks
Mark Scheble

Hi Mark,

Welcome to the forum! This is an interesting project. I did a similar project three years ago.

The sizes of the cardboard and the grid depend on the string length you choose to use. The string should be long enough so that the motion of the ball can be easily measured. You might want to play with the set up a bit to come up with a reasonable length. A string length (L) of 1 to 2 feet might be good a length to start with.

The cardboard should be 2L by 2L. I would start with a grid size of "2 in by 2 in". If later you find out that you need smaller grids, you can easily draw more lines to make "1 in by 1 in" grids out of your original grids.

I would suggest hanging the pendulum on something sturdy. With a person holding it, it is not as easy to hold it steady, and you will probably need an additional person to do this project. When I did it, I used a C-clamp to secure it on the edge of a large round table. I would also suggest releasing the ball from the same height each time. Instead of measuring how far the ball "curved" with just one swing, you could let the pendulum swing a fixed number of times and measure the change or displacement of some measurement. It might be challenging to control all the parameters involved in a consistent manner.

I love your idea of incorporating different pitches. However, I don't have any suggestion on how to set it up and measure it.

JChang