From: bpittenger (bpittenger@earthtones.com)
Date: Tue Dec 14 2004 - 07:58:40 PST
Date: Tue, 14 Dec 2004 10:58:40 -0500 Message-Id: <200412141058.AA2398290088@earthtones.com> From: "bpittenger" <bpittenger@earthtones.com> Subject: Baseball Experiment Ideas
Anita,
I guess that is a primary part of the whole experience of a good science fair experiment - identify variables, then eliminate them one by one except for the variable the student is testing. Encourage your student to list out each thing he thinks may change in each swing, and by doing this he will identify the variables he needs to address. He should come up with variables such as angle of approach of the bat, speed of the bat at time of impact, which part and side of the bat strikes the ball, angle and speed of the ball at time of impact (if any), spin of the ball at impact, energy level and technique of the batter, etc. In an ideal world he should be the one who comes up with these ideas, and makes the list. Then he needs to brainstorm ways to make each of these variables consistent for every test. I think he will soon realize that it will be difficult to make a well-controlled experiment if he uses a human subject to swing the bat. This is not the sort of thing that will happen in one short sitting.
If there is time, have him do this in stages - send him away for an evening to come back with variables. Then the next day for solutions, etc.
Once he figures these variables out, he could do some research by contacting one or more bat manufacturers to find out how they test their bats. Put the ball firmly in his court, so to speak (to mix metaphors?). He could start with an article such as: http://www.nisss.org/balltest.htm He may need some help with this article at first, but then he will pick up the terminology. He can use the vocabulary from this or some other article to expand his research.
He also would need to decide whether he is going to have the bat move to the ball, or the ball to the bat. If he wants the ball to move, then he will need a pitching machine of some sort and a firmly attached bat. If he wants the bat to move, he needs a tee for the ball and a hinged framework for the bat.
Students in our science fair have done this experiment with bats and golf clubs over the past few years. I think one even set up a kicker for a soccer ball. I did have one student test footballs with human testers. He figured out pretty quickly that such experiments are hard to control. The most consistent setups usually included some sort of hinge which forced the bat (or club) to swing at a consistent angle, hitting a ball on a tee. (A bat would need to be firmly attached. Perhaps the bat could be drilled, with a bearing inserted in the handle so the bat becomes an integral part of the hinge, or the bat could be bolted to a board which is attached to the hinge.) Then the amount of force needs to be addressed. I have seen students use bungee cords. Your student might realize that the elasticity of the rubber will deteriorate with use, depending on how far and how many times they are stretched. I suppose a spring could be rigged also. The spring would better retain its elasticity, but might be har
der to obtain, set up, and adjust. Then he needs to make each 'backswing' consistent. He could pull it back the same distance by setting up a stop of some sort.
Ultimately, although it is sometimes difficult, I am of the opinion that it is always best to leave most of this thought process to the student - guiding them on the process rather than the solutions.
Good luck!
Ben Pittenger
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