[The Tenth Blog] Electrostatic.

Today I went to a first birthday party for my mother's co-worker's daughter. Her name is Leura (after the city in Australia) and she's really cute. :] But anyway, since it was a birthday party, there were lots of balloons, which of course reminded me of...physics!

Objects can become charged by friction if they are rubbed together. I would not have done this at the party (sorry, not even for physics) because I would have looked ridiculous as well as made my hair all frizzy and such, so I'll just speak theoretically. If I had rubbed the balloon against my hair, both my hair and a balloon would have become charged. Since the rubber balloon has a greater electron affinity (Yay for chemistry. :P) than hair, it would pull electrons away from my hair (It is always the electrons that move! :]), making the balloon negatively charged and my hair positively charged.  Also, since charge is conserved, the net charge would be constant throughout the process. The balloon and my hair were both neutral at the beginning, and since electrons are simply transferred to make one object positive and the other negative, the total number of electrons and protons remains the same (equal), so the net charge is still zero. Now that we have created two objects of opposite charge, guess what? They'll attract! Because opposites don't only attract in real life; opposites attract in physics too. :] We would actually be able to calculate the electrostatic force that my hair would exert on the balloon using the equation 
F = kQ₁Q₂ /r² where k is equal to 8.99 x 10⁹ N • m²/C², Q₁ and Q₂ are the charges of my hair and the balloon, and r is the distance between them. I actually recall doing this as an experiment back in elementary school, but only now do I actually know the physics behind it (after, like, six years... Haha.)