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Unformatted text preview: Solutions for Hand-In Set #1 PHYS 212 - Spring 2007 Problem A2 — Repulsive Balloons Blew up the balloons (i.e., inflated them — I didn’t use any explosives or anything) and tied them to the ends of a piece of string. Let them hang, and eventually (after bopping each other a few times), they came to rest touching each other. (a) I wasn’t wearing a fuzzy sweater, so I rubbed the balloons on my head. Let them hang by the string again (holding string in the middle). The first time, the bal- loons stuck together. Then after I separated them again, they repelled slightly for a while — then one came up a little and stuck to the top of the other. Obviously, I hadn’t charged up the whole surface of the balloons. Try again, this time really making sure that I rubbed all sides of the balloon against my hair. This time it worked — the two balloons remained separated. It was actually kind of cool — the distance between the two of them oscillated around an average value of about 7 or 8 cm (it was difficult to measure, because I couldn’t bring anything close without affecting the forces acting on the balloons). Sketch Force Diagram for Left Ballon (Blue) T F gravity F e (b) As I pushed the blue balloon toward the red one, the distance between the two of them decreased. In fact, they decreased to the point where the two of them were...
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- Spring '08
- Force, Electric charge, metal ball, Fgravity