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Finding Junk May 2, 2009

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So I was looking through my room this morning, trying to tidy it up, when I came upon this pedometer sitting behind some books on my shelf.  I have absolutely no idea how old it is, I vaguely remember buying it, but it was really, really dusty when I pulled it out of its hiding spot, and the cover is already broken off.  However, the clear shell that encases the actual pedometer allows me to see all of the mechanical and electrical components that make up the pedometer.  The main component is the “arm/hammer” looking thing that moves up and down as you walk in order to count your steps.  I realized that this arm is magnetic and has a spring that helps the weighted arm bounce up and down easier.  I found out that there are two metal squares underneath the where the magnetic end of the “arm” swings, and that they read the magnetic flux induced by the magnet, which is what makes the pedometer “count.”  The spring is used to apply a spring force that makes the arm return to its “equilibrium” state when it isn’t moving up and down.  However, the spring constant is small so that the “arm” can still swing easily without the spring applying too strong a force.  I also noticed a capacitor on the circuit board, which I guess would be used to discharge whenever the “arm” swings over one of the metal squares to count a “step.”

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Ahupua’a Youth Environmental Summit April 26, 2009

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This morning I woke up early (very reluctantly) to go the the Youth Summit which is the main event of the year held by the Mayor’s 21st Century Ahupua’a Youth Ambassadors council that I am a part of.  During this summit, which was open to the public, several speakers from the board and water supply, rail transit, and wastewater treatment came out to talk.  However, I think that one of the most gross, yet interesting, presentations given was by the wastewater treatment people, not because it was all about poo in the sewers, but because it had to do with physics.  One of the main points the man made during his speech was that debris and contaminants such as cooking grease, paper towels (which are not made to go into the sewer system), roots, etc.  all contribute to clogging the sewer lines and causing sewage spills out of the manholes.  It is this concept that I was able to apply Bernoulli’s Law (P+pgy+0.5pv^2=constant) to explain why clogs led to overflows, although the basic concept is obvious.  As shown in the picture below, the pressure will increase if their is a clog in the pipes, therefore, the only way for the pressure to be compensated for is by the sewage rising up the manholes and creating a sewage spill.

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Family Fair!!!! April 19, 2009

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I’m sure almost everyone else in physics is writing something physics related to the family fair, but I couldn’t pass up the opportunity either.  Although I say numerous examples of physics at the fair, I must say that one thing that reminded me of Doc was the malasada sign that said: 1 Malasada=1 scrip, 2 Malasadas=2 scrip, 3 Malasadas=3 scrip, etc.  It made me want to pull the sign down and just write: 1 scrip per Malasada!  Some of the other examples of physics that I saw was how the wooden poles and ropes held up those massive tents.  After watching numerous people trip over those ropes which didn’t budge, I realize how strong those ropes must be in order to endure the tension placed on the ropes and the stakes that hold the ropes to the ground.  I also realized that when the malasadas were being fried, they only floated to the top when they were done cooking.  This was because as the malasadas are cooked, the puff up and air bubbles form in them, allowing the buoyant force to make the dough rise to the surface of the oil.  These were just some of the great examples of physics that I saw at the fair, which was yet again a ton of fun and very successful.

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Piano Physics April 12, 2009

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Yesterday my family purchased a new keyboard, which is a lot of fun to play with.  However, since the piano, like most other products, only come with half of the necessary accessories, we had to purchase a keyboard stand separately.  As I was assembling the stand, I realized how if it weren’t for physics, the stand wouldn’t be able to be set up, nor would it be able to hold the keyboard without collapsing.  When I was setting up the frame, I had to use a hex key to screw the frame together.  Because the hex key is “L” shaped, you can use either end.  However, the length of each side is different, and I learned in physics that torque=radius x force.  Therefore, holding on to longer end of the hex key makes it easier to loosen the tight screws and tighten the screws better without using excessive force.  Once I finished assembling the stand, I had to place the keyboard on top.  The stand design is an “X” shape that criss-crosses and holds up to 100lbs.  I realized that the weight of the piano also exerts a torque of the stand, but the lock at the central pivot of the “X” is strong enough to prevent the “X” from collapsing.

Lasers April 4, 2009

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Today has been an extremely tiring day cause I had ACT in the morning at school, then I had to stay till 4:00 since I had volleyball practice too.  It was like a regular school day since I was there so long.  Therefore, I don’t know how much longer it will be before I collapse on my laptop as I’m typing this up.  I’m already half asleep, so I’m having trouble coming up with a topic for the physics blog.  I just finished doing my physics homework (yes Doc! I did my homework), which was extremely confusing, but the thing that has stuck in my mind is lasers.  I am fascinated with lasers and although they seem like some kind of high-tech technology, they have common applications.  I am listening to music, so I recognized that it is a laser that is helping a sensor to read the microscopic lands and pits that hold the data.  I am also using a laser mouse to navigate the computer screen.  In this case, the laser helps a sensor to track the movement of the mouse on the mousepad.  And then, of course, I have my laser pointer, which is a ton of fun to play with.  As I just read, lasers need some energy source to create an environment in which the majority of the atoms are “energized,” and in the case of the three previous examples, that is batteries.

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I know its kinda hard to read because of the wall, but it says “Good Night,” which I feel is very appropriate for me right now.  “Good night.”

Mirrors Everywhere March 16, 2009

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This past weekend I was driving around when I realized how many mirrors drivers use.  There are your rear view mirror and two side view mirrors.  I learned that the side view mirrors state “objects in mirror are closer than they appear” because the mirrors used are convex mirrors, which in this case, create smaller, upright, and virtual images.  Convex mirrors are used so you can see more object (cars) in your mirror.  Convex mirrors are also used in the Iolani School parking lot around the turns as you go from floor to floor, but these mirrors are larger and have shorter focal lengths in order to make the objects even smaller and fit an even large view of the corner on the mirror.  This allows people to see “around” the corner.  These types of mirrors were also used in the grocery store at the top of the celieng, so employees can see everything that is going on to make sure that no one is steeling.  I realized this weekend how big of a part mirrors play in our lives.

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Jeff Mikulina – Blue Planet Foundation March 7, 2009

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On Tuesday I went to a lecture given by Jeff Mikulina, a speaker for the Blue Planet Foundation, on making Hawaii oil independent within the next decade.  I found his speech to be very interesting and related to the areas of science I am interested in.  Although he taught me many things I am already aware of, one major point he emphasized that really got me thinking was taking advantage of solar power.  Due to the sunny climate of Hawaii, solar power is the ideal alternative energy source, and his comment that amazed me the most was that on average, a roof in Hawaii receives enough sunlight with an energy equivalent of fifteen gallons of gasoline every day!  This fact alone really lead me to want to persuade my dad to install solar panels on our roof.  My dad has already been considering investing in photovoltaic roof panels, or at least solar water heating, and when I talked about Jeff Mikulina’s lecture, I think I gave him more reasons to buy them.  However, the only thing keeping my dad from buying some is the fact that they are pretty expensive, and since our house doesn’t use that much electricity, it is not very economical to buy them.  I think that spending a little bit more that we want to might be a necessary price to pay for improving our environment and reducing the impact of global warming.  As my dad weighs the pros and cons of solar panels, I figure there must be a more immediate solution I can make to contribute to Blue Planet Foundation’s goal of oil independency.  Since Jeff Mikulina also commented that 40% of the fuel consumed by the average American household goes to water heaters, one of the steps I can take to reducing my dependency on oil is reducing the amount of fuel consumed by the water heater in my house.  Since it has a dial that controls the temperature of the water (via consumption of fuel) I figured that turning the temperature of the water down a little bit will help save fuel.  This is just one of the steps I can take to make the world a better place to live in.

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Grillin Physics February 22, 2009

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This morning Dad was cooking some banana pancakes on the electric griddle, but the pancakes weren’t the only things that were delicious, so was the physics behind cooking these pancakes.  After taking a look at the griddle (when it wasn’t hot of course!), I noticed a large metal wire traveling along the under side of the griddle surface.  When I saw this, I noticed that this wire connected to were the power source comes into the grill from the AC outlet.  There is also a dial on the power input connecter, which varies the temperature of the griddle.  This connecter and the wire underneath the griddle are the physics behind what makes this griddle so hot.  The equation that can be applied here is P=I²R because the heat that the griddle creates comes from the giant wire underneath the griddle surface, and that heat is energy, equivalent to the P (power) in the equation stated.  Since so much heat is given off to cook the food, P must be a large number, and since the current is provided by the AC outlet, it is the same current applied to all other household appliances, therefore, the wire must have a large resistance in order to make the griddle so hot.  Also, the connector must vary the current entering the high resistance wire, so the connector must be a variable resistor (explained in my previous post).  Therefore, I in the equation above can vary in order to change the value of P, or the heat the griddle creates, since R cannot vary without actually changing the wire.  Of course, other factors such as temperature do play a minor role in affecting the resistance of the wire too.

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The Alarm Clock that Never Wakes Me Up February 16, 2009

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So while I was thinking about what I could write about for my physics blog this week, I just stared at my alarm clock at let time pass by.  But then, I realized that I was staring at the perfect example for my blog this week.  Since we just learned about DC circuits, I thought that my alarm clock must be an example for something we learned.  Now, although I’m not 100% sure on how my clock is made, I think that the dimming switch on the alarm clock can be explained by the use of a variable resistor.  As I slide the dial for the brightness of the display on my clock up and down, the intensity of the light emitted from my clock increases and decreases.  One way of explaining this is that the dial that I am spinning is the control for the variable resistor, which basically looks like this:

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http://www.ngfl-cymru.org.uk
   

The variable resistor works by changing the distance that the current must flow through a material with relatively high resistance.  The reason why this resistor can change the brightness of the display is explained by the equations P=IΔV and P=I²R and ΔV=IR.  We can use these equations to show that if the resistance of the resistor increases, than it will consume more of the power provided by the battery, leaving less power for the display to use (conservation of energy).  If the power that the display uses is reduced, then it cannot give off as much light, resulting in a dimmer display.

 

Chinese New Year February 8, 2009

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I know that I’m writing about Chinese New Year a little late, but I just felt that I had to talk about one particular lion dance that I saw.  When I went to Chinatown the Saturday before Chinese New Year, the most memorable thing I saw was the lion dance where the people in the lion costume were dancing on top of poles of different heights, which ranged from maybe three feet to as high as ten feet.  Although the physics behind it may be sparse, I still recognized that as the dancers moved between poles of different heights, their potential energy changes.  They have a higher potential energy when they are on top of the higher poles, and have less potential energy on the shorter poles.  Due to the conservation of energy, I could use the equation KE+PE = KE+PE to explain why it would be a lot more sore for the dancers if they fell from a higher pole.  This would be because at the top of the pole, they have zero KE, but a large PE, so if they fell, when the hit the ground, they would have zero PE, but in order to satisfy the equation above, there would have to be a large KE equal to the PE that the dancers had on top of the pole.  With a larger KE, they would hit the ground with more speed, and therefore more force, which is why it would be a lot more sore to fall from the higher poles.  Although the dances did slip off the poles several times, due to the light rain, they never did fall off and experience the pain of physics.

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