Last Physics B Blog :-(

Can you believe it? Physics is over. Part YEAH!, part :-(. But can you believe that I'm still seeing Physics everywhere? Of course, because it is! Well, on Friday night as I was drinking the last of my glass of water before I went to sleep, when I noticed a small black thing on the bottom of my glass (off the table, not in my water). However, when I drank enough water to pass below where the speck was, it moved. I suddenly though: "PHYSICS!" What I had just experienced was the refraction of light as it entered and exited different substances (air, glass, water, then air again). The picture above shows the refraction of light from an empty glass, but there was a huge amount of difference when the water was gone. The water must have caused the light to refract more than just the glass did (Snell's Law: N1sin(1)=N2sin(2)). It was a very interesting experience, reasuring me that I still remember something and that not everything has leaked out of my brain since monday afternoon, especially since I'm taking the Physics SAT on June 7. Hope that goes well.

Our AP exam was certainly an interesting experience; the multiple choice didn't seem bad, but that's what I thought last time (which didn't turn out too well). I hope I didn't make any horrible mistakes on free response, although I know that I did one problem wrong and was unable to correct more than a bit of it before time was called. Oh well, at least I defined my variables. :-)

But enough for Physics now. There are other finals to focus on now. And wasn't Junior Prom fun? :-) A nice way to close off AP exams (I took my last one on Friday afternoon, the last exam of all). Well, good luck to everyone, and I'll see you in AP Physics C next year, Doc! :-)

In the midst of all the AP's, Physics Final Exams, homework, and attempting to find time to sleep, I noticed a spontaneous bit of Physics the other day. In my windy Manoa home, where the bamboo bends nearly horizontally under some winds, I noticed that our closed front door (pictured above) was banging back and forth as far as the deadbolt lock (upper circle on the left) would let it. I then noticed the strong winds outside and realized.....Phyiscs!!!!!!!!!!! I decided that there were two possible explaination for this: one, the wind was pushing on the door, applying a force equal to the sum of (the masses of the air molecules times their acceleration), causing the door to accelerate inward until it hit the deadbolt; then when the gust of wind stopped, the door would return to its inital position from the force of the internal pressure in the house (F=PA). Scenario number two: the wind was not blowing into the door, but across it; therefore, by Bernoulli's Principle, the external pressure would decrease as the air velocity increased, pushing the door outward with the force of the net internal pressure, then returning as the wind speed decreased again. Or, perhaps, it was some of both, I'm not sure. But even the wind is a process of Physics; as a region of air increases in temperature, it expands in volume, decreases in pressure, and decreases in density, rising, making way for colder air to fill the void and creating wind. The opposite is probably true as well, and that's probably what happens in the valley at night. It sure makes for an interesting knocking noise while I'm supposed to be eating dinner or doing homework. :-)

Physics At Dinner

I know that this may look a little funny, but this was my parents' and my dinner (halibut with butter and rosemary). It was really good. While this may not seem very Physics like, I found myself relying on Physics to serve my dinner. When my dad first took the dish out of the oven, it was too hot to touch and I didn't have an oven mit so that I could steady the dish while I served myself. So I just used the one hand with the tool pictured. However, the fish was sticking to the pan, therefore making it hard to serve with only one hand. At first the dish didn't slide, then I felt that I was reaching the limit of static friction. Afraid that I would have to travel the five feet to get an oven mit, I tried different angles with the server, trying to find a place where the dish would neither slip nor spin. Eventually, I was able to serve my food without overcoming the maximum static friction force, although I was very close. I guess even though the dish is rather heavy (giving it a large normal force for a larger friction force), the fish was rather stuck. I also noticed other Physics connected with food and microwaves. When I heat up my lunch, which today was leftover spaghetti, I have to place a piece of wax paper over the top to keep it from splattering. This is because the water in the sauce turns to steam and, as it gets hotter, it expands (V1/T1=V2=T2 at constant pressure). If the reaction does work at constant pressure, the air is released from inside at a non-messy rate. However, if this is an isochoric instead of an isobaric process, the pressure rises with the temperature (P1/T1=P2/T2) and will eventually overcome the sauce's ability to contain it. At this point, the bubble explodes and sauce splatters all over the inside of the microwave, an occurence that is really hard to clean. That is the reason for the wax paper, unless, of course, you are like me and microwave food until it's cooked a second time, then sometimes the spaghetti explodes out the sides. That's always fun. :-)