2/2/10 Class

Today, we wrapped up kinetic and potential energy and began our exploration into electrostatic force.

We finished off Chapter 5 with one last problem involving a bungee jumper jumping off a cliff. Using the given information, we had to calculate various things such as the max velocity, the point of max velocity, and the spring constant of the bungee cord. The big insight used to solve this problem was realizing that . Using this, you can set to find the spring constant of the bungee cord and through that the rest of the answers.

After a short break, we began our journey into the wonders of electrostatic force with a hands-on experiment involving "magic" tape. We put layers of tape on the desks and quickly ripped the top layer off and observed the way this top layer of tape interacted with its surroundings (i.e. other pieces of tape, paper, etc.). When two top tapes came in proximity with each other, they tended to repel each other, demonstrating a new type of force: electrostatic force. Other properties of the tape we observed was that it attracted pieces of tape from the bottom, rather than repelling them. Mr. Burk also showed us similar interactions between a plastic rod and paper as well. This energy comes from the displacement of electrons in the objects being rubbed together; when electrons (which are negative) are lost or gained, the charge of that corresponding object becomes more positive or more negative. When two objects have opposite charges, they will attract each other.

That's what we did in class today. Next scribe is Margaret.