I am color blind

Left: Ishihara Plate displaying the number 45 (source: http://www.toledo-bend.com/colorblind/Color45.jpg)

I am color blind. I have deuteranomaly , which means that I perceive colors utilizing all three cones (red, green, and blue) in my eyes, but I have trouble with sensing colors with my green cones. Others forms of color blindness are classified under monochromacy and dichromacy. Those individuals perceive colors using only one or two cones. Because all three of my cones are functioning, my color blindness is not as severe as those with mono or dichromacy, but I still occasionally run across problems with my form of colorblindness. Because I have trouble with the green cones in my eyes, I am more sensitive to red light, and thus I have trouble distinguishing between some colors, especially red and green. I can easy identify most of the colors I see, but I cannot pass the Ishihara/PseudoIsochromatic Plate test (I missed it by one) that is used by the U.S. military. Individuals who cannot pass the Ishihara/PIP or FALANT (used as an alternate test by the U.S. Navy) are restricted from certain duties, one of which is aviation. In aviation, red and green lights are used to distinguish between the port (left) and starboard (right) sides of an aircraft to help pilots determine the orientation of other aircraft they see in the dark. Red and green lights are used because the longer wavelength and thus lower frequency of red and green light waves are less susceptible to scattering in the atmosphere, and can therefore be seen at the greatest distances. I can actually distinguish between the red and green used in aviation and can still get an unrestricted civilian pilot’s license from the FAA (there are actually a handful of colorblind airline captains!) if I pass the more practical color test in which I am tested with a light gun from the control tower and asked to identify if it is displaying red, green, or yellow, but military is most likely out of the question because of their stricter requirements. But other than that, being colorblind is awesome!

*sigh*

Water and Flames

Today I went to the open house for the University of Hawaii’s Institute for Astronomy. There were a lot of cool things there, including devices called Ruben’s Tube and Kelvin’s Water Dropper (the same Lord Kelvin who developed the Kelvin scale for temperature). The Ruben’s Tube is a long pipe with many holes along the top of the pipe. It is sealed with a speaker on one end, and tube connected to a propane gas tank on the other end. The speaker creates sound waves, which are longitudinal waves that have high and low pressure areas, within the pipe. The gas provides fuel for a flame, which responds to the low and high pressure areas created by the sound waves. Higher pressure areas have taller flames because more propane gas is escaping through the hole above it, while lower pressure areas have shorter flames because less gas is escaping through the hole above it. The attendant there told me that with a steady pitch and no wind, the flames will create a sinusoidal wave. Kelvin’s Water dropper features a large water reservoir suspended at the top of the device, which releases drops of water down two separate tubes. Before falling into a metal bucket below the reservoir, the water droplets travel through a tube with a conductive metal ring that is connected to the bucket opposite of it. Because of the ions from minerals that are contained in water, one bucket eventually becomes more electrically positive than the other, creating a voltage difference. This creates a visible spark between metal spheres attached to each bucket. As I walked around looking at other exhibits I noticed that many aspects of astronomy relies on physics as well as chemistry. And I here I thought astronomy was just looking at stars!

HECO Meter

I thought it would be ridiculous if I dressed up in my MARPAT uniform for this picture, so I did.

Also, new episode of 24 tonight. WHAT'S JACK GOING TO DO?

Electromagnetic Fields

Electromagnetic fields are everywhere, because, as we learned in physics, an electrical currents create electromagnetic fields. Hans Christian Oersted found this out on accident when he had a wire with current flowing through it and a table full of compasses, so I thought it would be a great idea to go around the house this weekend with a compass to observe for myself the effects of electromagnetic fields. It was cool (For real!). My compass reacted according to the strength of the electromagnetic field generated by whatever device around the house I tested because the compass is simply a magnet that points to a magnetic south pole. I tested my compass with a cell phone, a clock radio, and a 500W computer power supply unit. The compass seemed to react most to the cell phone at its base, which is where I suspect the antenna is located, and second most to the clock radio. Yay for physics observations in everyday life!

EDIT (3/11/09): Video is up now.



EDIT (3/10/09): I have to make a correction to the concept explained in this post. Upon closer examination, I noticed that my phone caused movement of the magnetic needle of the compass even while it was turned off, so the electromagnetic field could not have been the main factor for the needle's deflection. Whoops =(. Through further research, I found that it was probably the magnet in my phones speaker that caused the deflection. This is supported by the fact that the strength of the attraction/repulsion is stronger as the needle gets closer to the speaker area on my phone. Furthermore, the clock radio also has a speaker. Magnets are a component of a speaker. From my video, I can conclude that the south pole of my phone's speaker magnet faces in the same direction as the face of my phone, and north pole of the speaker magnet faces the same direction as the back of my phone.

Oops..

Last night I was a bit careless and I accidentally bumped a small exposed power connector while using the computer. Usually, that cord would be connected to a fan attached to the side of my case, which resists the current flowing through it, but I had removed my side panel because I needed to swap some parts out of my computer. I get pretty lazy sometimes, and after I swapped the parts out, I didn’t bother replacing the side panel and hooking the fan back up. That was a huge mistake. When I let the exposed power connector touch the conductive metal of my computer’s case, I short circuited my computer because there was little resistance (compared to the resistance of the fan) through the case. Luckily, due to the short circuit protection built into the power supply, I was able to get my PC (no components seemed to have been damaged) running again within moments. Hooray for safety features!

Combat Boots

A few weeks ago I bought a pair of Magnum combat boots for various reasons (working, airsoft, hiking, etc). They are surprisingly light and comfortable. The tag on the shoe mentions that it is “slip resistant.” This means that, as a whole shoe, the boots have a very high coefficient of static friction. Because the force of static friction is directly related with normal force and the coefficient of static friction, a higher coefficient of static friction means that it takes more force to over come the force of friction and "slip". To test this, I went walking around in my bathtub with the boots on, and it was awesome. It was very hard for me to “slip” (where the force of the forward motion of my foot exceeds the force of friction provided by my boots) even in a puddle on the smooth surface of the bathtub. This made me wonder, however, why causes such high coefficient of friction. I initially thought it was the material, the rubber soles, but I also have rubber slippers, and they slip (no pun intended) very easily under the same conditions. This drove me to research a little further on the internet about friction. The answer was water dispersion. The soles of my boots are designed in such a way to disperse water over a larger area. Water acts as a lubricant, which reduces the coefficient of friction. Because my slippers are rather worn out and are almost completely smooth at the bottom, they don’t disperse water very well, and therefore get the full lubricating effect of water.

These suck at water dispersion =(

The boots, however, have many grooves in which water can go into so there is less water lubricating the parts of the sole that come in contact with the ground (or whatever surface I’m walking on).

These are awesome at water dispersion =)

Walking in a bathtub with boots on can be a fun an educational activity!

More Torques, Please

In an earlier post I wrote about forces acting on the joystick I use for flight simulation. After learning about torque, however, I noticed that there is also torque involved in manipulation of flight controls. When my hand is in the normal position I use for flying fixed winged planes, I apply a force of F, which varies depending on how much and at what rate I want to bank/yaw (as mentioned in the earlier post, the more I want to bank/yaw, the more force is required because of the spring), multiplied by the lever arm distance (about 12cm with the base acting as the fulcrum and the middle of my palm acting as point of push force), to create a torque of 0.12F Nm. When hovering in a helicopter or flying in formation, I must make very minor adjustments in my flight controls and there is no room for me to be ham-handed with my controls. I learned a while ago that it is much easier to make these fine adjustments by resting my wrist on the base of the controller (Real helicopter pilots rest their hands on their thighs, since their control stick is usually in between their legs). This not only allows me to apply much less force on the controller, but also significantly decreases the lever arm distance. Since torque is directly related with both lever arm distance and force applied, the torque I apply is also lessened, thus lessening the chance of me over controlling the aircraft.