Friday, January 29, 2010

A dangerous magnetic object!






Sorry, you'll have to deal with my fail paint skills this week since I totally forgot to take the picture I was intending to take...

This rather intimidating, scary thing is actually a collector for pins and needles and the like. No, it's not mine. Yes, it exists in real life. Yes, someone needs to buy this person a REAL pincushion. In any case, it clearly demonstrates electric fields. The magnetic pin cushion keeps the metal pins and needles from escaping. They must have opposite charges, and therefore create a force equal to E*q, or the measurement of the electric field times the charge of the needle. Luckily, this force is greater than the weight force of the needles, or they would all go clattering to the floor in a dangerous mess. Unfortunately most of the needles and pins here are rusty and leave strange rust marks on the fabric when you use them...

Ten points to anyone who can guess the rather odd place where this is from... It's not anywhere that you would expect. :P

Whee for lots and lots and lots and lots and lots of random sewing... 2 done, 30 to go in a week...

Sunday, January 24, 2010

A cabinet door


On the cabinet in my bathroom, a magnet holds the door closed. This means that one side (maybe the door) has a strong negative charge and the other side (maybe the cabinet itself) has a strong positive charge, so there is a force that pulls each toward each other. The hinge, however, creates a force that wants to force the two apart. If the electric force of the door magnet and cabinet magnet is not greater than the spring-like force of the hinge, then the door will not stay closed. The electric force of the two magnets can be calculated using the equation F = k(charge of door)(charge of cabinet)/the distance between the two ^2. This means that the force is constantly changing, increasing as the door swings more closed and decreasing as the door swings more open. The spring force of the hinge decreases as the door swings open, and increases as the door swings open. Unfortunately, we don't have any way to measure the charge of the door magnet and the charge of the magnet on the cabinet, so I don't have to do the calculation....

The door doesn't stay closed, as you can see in this picture, so the magnets are too weak for the electric force to overcome the force of the hinge. Cabinet = fail.... :P

Friday, January 15, 2010

Bouncy Ball


At the robotics sleepover last weekend, we started playing with a super bouncy ball. Apparently you can throw it around 25 feet or more up if you throw it at the ground really hard. Since I was weak, I could could only get it 15 feet or so, but the first thing that this made me think of was conservation of energy. (Yes, I know, physics geek. :P)

Since the ball bounces really high, most of the energy of me throwing the ball downwards must go back into the ball as it bounces back up. For most balls, the kinetic energy of throwing the ball goes into sound or other forms of energy when it hits the ground, but for this ball most of the energy must go into potential energy and then kinetic energy. If you calculate that the ball goes 25 feet up, since the acceleration of gravity is -9.8 m/s^2, the velocity of the ball at the bottom was 22.1 m/s. This means that it's initial KE was 1/2mv^2, so if you pretend that the ball was 0.2 kg, then the KE is equal to 98 J. At it's highest point, the PE must be near 98 J, and most of it must not be lost if it goes so high on the next bounce.

Sunday, January 10, 2010

Ripples


Last week, a bunch of my friends from robotics slept over at Emily's house, which is really close to the water of Pearl Harbor on Ford Island. Two of us couldn't sleep, so we ventured outside at 5 in the morning to watch the sunrise, though because of a combination of sleep deprivation and laziness I didn't pull out my phone to take a picture of it. It was cool, even if we were facing the wrong direction to see the Arizona memorial or the sunrise. As the sky gradually got lighter, I could see the ripples on the water, which was about 10 feet away . Suddenly, a small speed boat went by. A minute later, we heard a strange sloshing noise.

It took a couple of seconds for us to figure out that the sound was the waves made by the speed boat, although the boat had passed into the distance a while ago. The waves reached us so much after the sound and sight of the boat had passed because the wavespeed of the sound and of the light that allows us to see the boat was so much greater than the wave speed of the waves. However the amplitude and wavelength of the waves was much greater than that of the sounds. When the waves hit the shore, the energy of the waves changed to kinetic energy as the pebbles on the beach slide back and forth, and the collisions between the pebbles caused energy in the form of sound waves to be made.

I didn't take a picture, so we'll have to deal with google ones for now... :P Though this is pretty close to what it looked like.

Friday, January 1, 2010

Personal Response on The World Is Flat: A Brief History of the Twenty-First Century by Thomas L. Friedman


Frankly, the book The World Is Flat by Thomas L. Friedman was by far not the most interesting book that I have ever read. However, it may have been one of the most truly educational and relevant things that I have ever read for school. When I first read the title, The World is Flat, I couldn’t imagine what this meant. I now understand that the author isn’t ignorant of simple scientific principle like I originally thought, but using a metaphor to talk about the way that new opportunities for global collaboration are being opened to everyone.

I actually found this book enlightening and depressing at the same time. Friedman was saying that my generation will not have the ease of finding jobs that our fathers and grandfathers did, because of increased competition from India, China, and other developing countries. New jobs are being created, but we must work harder to get an education and continue to learn ways to be not simply “vanilla,” as Friedman puts it, but a cherry on the top of the sundae. We must be something that is special and valued, not something that can be outsourced to other countries, and create niches for ourselves. When Friedman made the example of the private school where international parents complain there isn’t enough homework, and white middle class American parents complain that there is too much, I thought of ‘Iolani. Would the standards at our school really stand up at an international level? Are we, as students, really prepared to be competing on an international level?

Even many of the students at our school are not actually American citizens. Instead, they come here (with or without their parents) to get a better education and, their parents hope, a better life. I’ve clearly seen the cultural differences that Friedman mentions between first generation immigrant families and the more relaxed third or fourth generation American families. The new immigrants seem to be more involved in their children’s lives, and more likely to encourage them to get straight A’s and aspire to become doctors or lawyers.

This book has definitely changed the way I think, even if I had to slog through it by forcing myself to read it page by page. When I visited Costco with my family, I thought about how all the different products go through a national supply chain to be shipped here. When I went to Walmart, I resisted the urge to inspect the pallets of unopened boxes for those RFID tags that Friedman mentioned, and wondered as I went through the checkout if right at that moment the producers of fish food and flour were rushing new shipments to the warehouses to replace the ones I was taking with me. I wondered if the benefits that Costco workers gain are better than the financial benefits that Walmart as a company enjoys. Even in the McDonald’s drive-through, I began to see signs of outsourcing. Often, the person you speak to when you order at the drive-through isn’t in the McDonalds at all. Instead it is someone on the mainland who takes your order, then sends it electronically to the window where you can pick it up minutes later.

This book is long, with so many examples and references that I felt that the author must be repeating himself. I can’t really see anyone reading this for fun, though, and I’m not sure how much the content will really help readers. It is educational, and shows you how the world is widening and becoming more equal in most places, but even the author doesn’t know the secret to success or even survival in this new world of Globalization 3.0. His best advice is to simply continue to learn and change as the world changes around you. He doesn’t think that globalization should or can be stopped, but that we must adapt to it and continue to succeed as a country. I just hope I have enough ambition and eagerness to learn that I can survive in this new, flat world.