Unit VIII
Discussion on circular motion with help from a flying pig on a string. At a constant speed the velocity changes due to a change in direction and the acceleration changes due to the changing velocity. So then which direction are the unbalanced forces? Turns out they are in toward the center of the circular path. This was illustrated very well while trying to make a bowling ball move in a circular path on the tile in the hallway. In order to accomplish this feat, an applied force in toward the center of curvature was needed on the bowling ball. Great demo!
Another demo consisting of a triangular piece of whiteboard tied at the corners with string that comes together above it like a swing and a cup of "water" balanced on the whiteboard was demonstrated and discussed. When swung in a circle, the cup stays on the board and does not spill or come off the whiteboard. This can be swung in a vertical or horizontal circle with the same outcome. At any instant, the cup has a velocity component to a point tangent to the circle. This means that it wants to travel in that direction. However, in the next instant the cup travels to that point where the previous resultant velocity was taking it and it cancels out that previous motion. This hurt my head a little, but does make sense. In a nutshell, no matter what, if you are moving in a circular path, there has to be an unbalanced force pushing it in. This also gave rise to the concept of centrifugal force. This force is actually the sensation of being pushed outward when traveling in a circular path.
As always, each demonstration or conversation has some type of story associated with it. These always help to point out the ideas and concepts quite well and are also pretty funny. Students love to hear stories in class as it allows them to relate to the instructor on a more personal level. Don is truly the master of storytelling, proven multiple times during our evening discussion sessions!
After a most generous raffle of various materials, (Thank you!!) things wound down and we said our goodbyes. This has been a truly exceptional experience for me. Dare I say game changer or life changing? I most definitely think so. I can only hope I can do justice to the modeling concept in my own classroom. Plus I was able to meet some really awesome partners in physics throughout the state.
THANKS AGAIN TO EVERY SINGLE PERSON THAT MADE THIS HAPPEN!!!!!!!!