Summer Driving.....

PHYSICS HAS BEGUN AGAIN!!!!!!!!!!!!!!!!!!!!! Wow. Amazing how fast time flies. But, despite the fact that I was hoping to relax this summer, to little suprise of mine but to the dismay of my friends who also wanted to relax during summer, I saw Physics everywhere! One place where I saw Physics like crazy was here: driving..... Yes, I just got my permit this summer, took drivers ed, and have begun to drive. It has been a very interesting experience. First of all, I discovered that the "accelerator" really is an "accelerator;" I have had to constantly adjust the pressure on my foot because if i hold it in one place, thereby applying constant force, my speed keeps increasing, thereby surpassing the speed limit. Not good. I also have been having problems finding the correct amount of normal force to apply to the steering wheel while trying to let it spin back to strait after a turn so that it doesn't turn to quickly. Unfortunately, my hands tend to sweat whenever I even think about grabbing anything, so the coefficient of kinetic friction between my hands and the steering wheel is often changing. And then there's trying to figure out how much brake to apply while going downhill, and how much gas to apply to continue of a hill at a constant speed, where objects that I see in the mirrors really are, when do I turn to get into a parking space, AAAAAAAAAAAHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!! scary...... :-) Oh well, I'm beginning to get the hang of it. :-) Lots of Physics in driving, I've discovered. Now, if only driving could help me learn everything else firsthand, that would be cool, but I think I'm just about maxed out on multitasking while driving. I can learn everything else elsewhere. Go Physics!!!!!!! :-)

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. :-)

Falling Cups

This was a weekend of scientific experiement and observation (as well as other forms of procrastination) for me. On Saturday morning as I searched for a sugary snack to eat while I tried to get some homework done before going shopping for prom dresses, I found a can of "all natural" 7UP in my fridge. When I poured it in my glass, I found that streams of bubbles were coming from the same points on the bottom no matter what I did to the glass (no, I didn't turn it upside down). I then hypothesized that there were small irregularities in those spots, as I remeber from Chem that bubbles form on irregular spots, at least when water boils. So I found a glass that my dad had dinked up the bottom by stirring liquid with a spoon and poured the other half of the can in, and found a noticable column of bubbles coming from the center with all the dinks. I have support!!!!! And this was before I really even got into my homework at all. But I know, that's Chem. Here's the simple but funny Physics encounter of the weekend. As my mom and I got home today (Sunday) and were unloading the car of our few purchases and other stuff, my mom brought up the cups of water we had been drinking. To make things easier, my mom stacked two of the cups one inside the other. She then forgot that there were two cups and took hold of the top of the top cup. Normally they would stay together because the static friction force on the two surfaces of the cups was enough to hold up the bottom cup. However, in this case, we did not drink all the water. Therefore, the weight (mg down) of the bottom cup plus the weight of the water was enough to overcome the maximum static friction force dictated by the coefficient of static friction of the cups, creating a net force pointing down. Thus, the cup slipped off, hitting the wood floor of our house with acceleration -9/8 m/s^2 (or g), not leaving a dink but resulting in a large puddle of water on our nice wood floor that had to be wiped up before it hurt the finish. The water splashed out of the cup, obeying the law of conservation of momentum, at least at first, giving the many water droplets large velocities in the same general direction to account for the large velocity and mass of the dropped cup. Thus with these large velocities, the puddle was large as well, for many dropplets flew far away. But no harm done, plus I got to explain to my mom the Physics involved. I felt smart. :-)

Oily Physics

Talk about a Physics packed weekend! I probably saw the most Physics during Family Fair at the game tents, as many of the games relied on projectile motion, especially the Lani Moo, baseball, blast-a-ball, and shoot-the-ring-onto-the-bottle games. However, a knowledge of the workings of momentum and energy are also in order for the plate/octopus dime toss and the floating glass dish + ping pong ball games, as too much energy in the projectile will make it bounce out and you will lose. :-( However, my blog this week is not about Family Fair; it's about the Arizona Memorial. Although I admit that this is perhaps not the best place to be thinking about Phyiscs, I happened to notice that oil was still leaking out of the ship, almost directly below the memorial. However, the first oil that I saw was not rainbow in color; it was white. I first thought that this must be very thin oil, too thin for there to be a phase shift in the two reflecting rays and have constructive interference at any certain color. After seeing a new drop of oil expand into a rainbow of colors and then become this ghostly white sheen on the water, I decided that I was correct. Above I've pictured something like what I saw. However, this oil also led me to another Physic note. Remember the sunglasses from last week? I wore them to Pearl Harbor and Fair. As I was looking at a particularly large area of rainbow, I saw a section in the middle that had no rainbow, appearing as the outside did behind my dark polarized sunglasses. I was curious why this occured and, preparing to try to find out, I picked my head up from a slanted position to strait. But in doing so, I got a better answer than taking off my glasses would have done. As I turned my head, the rainbow disappeared, leaving only the water looking slightly darker than usual, and the ability to see the dark black thick oil floating in the water. I guess the rainbow coming from the thin layer of oil must be polarized, otherwise this would not have worked. I wonder if it is just the light off the oil, or if most light off the water is polarized as road glare is, and that's why polarized sunglasses work so well?

Sunglasses at Night...Late Night

My, we know so much now, don't we? And we've finally hit the long, hard, month of review before the AP exam! Wow. In fact, as I was sitting and reading my online Physics book at my computer before this past test, I discovered some very interesting facts about my computer, and the way I found this out may seem a little strange. If you are wondering about my picture, no I did not just finish watching Blues Brothers or sitting at the beach. In fact, I was trying out my new sunglasses to make sure they were comfortable(I broke my old ones a while ago), with a very inquisitive look on my face. However, this fact combined with a small quirk of mine brought me some valuable Physics insight. Here's the quirk that some of you may have noticed: I sometimes sit with my head inclined to one side or the other, depending on what I'm doing. At this particular time as I sat at the computer and absentmindedly turned my head, I noticed something: the screen changed colors. Or actually it didn't change colors, but it got dimmer. I then remembered that my sunglasses were polarized. As I turned my head to the right, the screen got darker until it nearly disappeared. Then as I turned my head to the left, I found that the position of least change in light intensity occured at just about ninety degrees from the position of darkness. This was consistent with the design of polarized lenses, which have very thin dark bands running either vertically or horizontally depending on their purpose. Because of this, only the vertical or horizontal components of all light waves reaching the lens are allowed to pass through to the eye. Therefore, as I turned my head from the brightest point to the dimmest, more of each light wave was being blocked out until almost all of all light waves were blocked. I've included pictures (yes, I am writing this entry in the background) so you can see what I mean. Cool, isn't it? :-)