Physics of the Washing Machine

Recently while doing my laundry, I noticed a cone shaped receptacle at the top of the central shaft of my washing machine. My roommate told me it was for fabric softener, and that the cone holds the liquid in place until the spin cycle, at which point the fast rotation of the shaft causes it to migrate out to the edge of the cone, where it can then drip over the edge into the bottom of the washer. I wondered, given a particular cone steepness, how fast would the shaft need to spin to overcome the force of gravity holding the fabric softener in place? As you can see in the force diagram, we assume the cone is symmetrical with a radius “r” and angle of steepness “θ”. Ignoring friction and viscosity effects, there are two forces acting on the drop of fabric softener: a normal force “N” and gravity, which is simply the mass of the liquid “m” multiplied by the gravitational constant .

At the threshold point where all forces are balanced, the liquid does not accelerate in any direction. Any rotational velocity higher than that will cause the liquid to migrate out of the cone. At the threshold velocity, the vertical component of the normal force equals the gravitational force:

And the horizontal component of the normal force equals the centripetal force:

By solving this two equations simultaneously (by substituting for N), we find that the threshold rotational velocity is determined by:

Where the angle of steepness is somewhere between perfectly flat and vertical:

Surprisingly, the mass of the liquid has no effect on the threshold speed. Considering the cone in my laundry machine has a radius of about 2cm and an angle of steepness around 45° (=π/4), the threshold velocity would be about 0.443 m/s. Dividing this by the circumference of the cone (0.126 m) gives an angular velocity of about 3.5 rotations per second. In other words, the washing machine must rotate at least 3.5 times per second to “push” the fabric softener over the edge of the cone. Seems pretty fast! No wonder washing machines consume so much electricity.

 

Annonaceae- My Favorite Fruit & Its Family

My favorite fruit in the world is Guanábana (Annona muricata, aka “Soursop”).

A very large guanábana fruit in a Colombian tienda. Photo Credit: jjrestrepoa

Native to Latin America, it also grows in tropical Southeast Asia and Africa. In the Philippines it is called “Guayabano”. The first time I tried it was in a smoothie at the Café Havana in Greenbelt Mall, Makati. Since I returned to the US, I have vainly attempted to find the fruit in grocery stores and Asian markets, although I did get to try it again on a recent trip to Puerto Rico. Right when I was about to give up, however, I discovered that another South American fruit, the cherimoya, is in the same genus and is more widely available (at least here in Charlottesville). Furthermore, one of my coworkers shared with me that there is a fruit called pawpaw found in North American forests that is in the same family. Actually, it’s the tree with the gigantic, deciduous leaves. Kentucky State University has a major pawpaw research program, and offers a great general information site. Here’s our exchange, as well as some comments from my college botany professor:

[ME] I looked up pawpaw and it is indeed in the Annonaceae family. In fact, the genus to which it belongs, Asimina, is one of the only temperate representatives from the family. Most of the other edible fruits in that family are from the tropical genus Annona. Annonaceae, along with Magnoliaceae and the nutmeg family Myristicaceae, are all very closely related in that they are from a “primitive” (ancient) lineage of flowering plants, lacking well defined petals or sepals and with leaves characterized by a “ranalean” odor of aromatic, essential oils when crushed (botanically, they are part of the order Magnoliales).

[STEVE, my coworker] Incidentally, there are lots of pawpaw trees around the lower parts of the Old Rag hike, but I haven’t yet seen one with fruit.  I have seen them with fruit near Sugar Hollow reservoir and, as I mentioned, a few weeks ago [another coworker] brought one in that he picked near the Monticello trail.

[DR. KNOX, my professor] Yes, I’ve had cherimoya in Peru, and it is delicious.  It’s been so long since I’ve eaten it and I only had one infructescence, so I don’t remember much, other than that it was sweet and similar to pawpaw.  In Cherimoya, the many pistils in each flower enlarge until they are packed tightly together to give an accessory fruit that looks like a grenade.  I’ve seen other Annonaceae growing in the wild in Panama and Costa Rica. As for pawpaw, fruit production seems to vary a lot from population to population.  For example, I have watched the many pawpaw tree on our back campus for years, and though they form many flowers, I scarcely ever see fruit. I’ve  wondered if they lack the appropriate genotypes to set seed and fruit, or if conditions for pollination, fertilization, or fruit development are not very good there.  But then downstream about a mile along the Maury the trees usually do produce  fruit.

So, why isn’t this fruit more widely cultivated and consumed? According to the Christian Science Monitor, the fruit’s rapid spoilage rate, poisonous seeds, carrion-fly pollination mechanism doomed its prospects for commercialization. Nevertheless, I hope you all won’t hesitate to try one of the delicious fruits from this fascinating plant family if you get the chance- there might even be one in your own back yard (just omit the seeds, like a watermelon). I think I’ll go eat one right now!

 

Singapore

26 March 2008 (click here for photos)

Singapore lived up to its reputation for cleanliness and efficiency. After taking the stunningly modern metrorail from the spotless airport, I got off in “Little India” and stayed at a hostel surrounded by Tamil (South Indian) businesses. My first dinner at a Tamil restaurant was so spicy, the sweat was pouring down my face, but it was delicious, with curried lamb and many unusual vegetables. One highlight of visiting Singapore was meeting Dixi, a brilliant Filipina friend recommended by AM in Manila who was studying environmental engineering at Nanyang Tech. We met for dinner (I tried stingray for the first time!) and walked over to take photos with the Mer-Lion, the mascot of Singapore. It was great to share a conversation ranging from Biblical exegesis to carbon sequestration and the burgeoning local water engineering industry. We were joined later by the intriguing Shahirah, who shared stories about her work in public relations (did you know Singapore has the world’s largest Ferris Wheel?), and her Muslim faith. On another day, an enthusiastic Singaporean couchsurfer named Geraldine showed me around the city. I was very impressed by her encyclopedic knowledge of her city, and she was particularly fond of the wide variety of architectural styles found here. For example, within a one mile walk, we passed a Hindu Temple adjacent to a Chinese one, behind which a massive skyscraper was under construction. Further along, a shiny bronze hotel with an Ayn Rand theme abutted a Mosque. Finally, we passed by the fortress-like central police office; the courthouse, which looked like a UFO was landing on top; and the spiky, irregular, durian-shaped convention center. In fact, the durian, a pungent, creamy fruit resembling a spiny green basketball, is a great metaphor for Singapore’s two salient features:  cultural diversity and authoritarian governance. While ethnic “Straits Chinese” make up 75% of the population, they manage to coexist with sizable Malay and Tamil minorities, as well as more recent immigrants from the Philippines, Indonesia, and Europe. While racial tensions did spur Singapore’s secession from the Malay Federation in 1965, they have since abated, although as Geraldine explained it is still rare to see intermarriage between different ethnic groups (in this way, it reminded me a lot of the United States. We are still more of a “patchwork quilt” society than a “melting pot” society). Despite their cultural differences, almost everyone in Singapore loves durians, and it has been incorporated into all kinds of fascinating culinary creations unique to each neighborhood, from ice cream to fish curry. Similarly, the durian fruit illustrates the draconian force of law in this city-state: carrying one on a subway car or metrorail is banned, and carries a hefty fine!

After a long day of walking, Geraldine, whose hospitality was as expansive as it was spontaneous, invited me to join her family for dinner, which I thoroughly enjoyed. Her Mom was an excellent cook, and her Dad an engaging interlocutor; he encouraged me to return to my family “by hook or by crook” because it’s not good to be far away from home for too long. I found this strong, traditional emphasis on “family-first” to be a widespread ideal in many Asian nations. Geraldine’s younger brother Aloysius was very curious about US History, and I tried to objectively describe the conquest of the Native Americans, and the shame of the slave trade, as well as our ideals of free enterprise and individual freedom. While Singapore is probably an even greater exemplar of capitalism than America, it starkly differs in personal liberty. As Aloysius explained, most middle-class Singaporeans such as his family cannot afford to own or drive a car due to onerous taxes. When I replied that they have an excellent public transportation system, and that taxes on cars and automobile fuel reduce congestion and pollution, he elaborated that personal mobility has an important, almost spiritual significance for a young person, no matter which country they live in. Indeed, one of the favorite pastimes among guys his age is to go over the border to Johor Baru (Malaysia), where the laws are laxer, and drive a fast car on a back road. Furthermore, Formula-1 racing is as popular in Singapore as NASCAR is in North Carolina! Finally, discussing the sub-prime crisis in the economy, we all agreed that it was caused by people borrowing too much to finance excessive consumption. Both Geraldine and Aloysius expressed concern that despite Singapore’s current economic strength (2nd busiest container port in the world), younger generations may become decadent and less pragmatic. Aloysius even compared Singapore to Venice, fearing that it too may someday sink into the water and become a relic of past glory. Nevertheless, my own impression of this bustling, diligent citadel on the tip of Asia was a refreshing departure from the organic chaos that marks so many other Southeast Asian cities. While I don’t think I could live in a city that bans chewing gum (indeed, I even found myself missing the acrid fumes of the streets of friendly Manila at times amid the sterile Singaporean causeways), it was very pleasant to visit, and I can see why so many people find it a great place to do business, receive medical care, or get a world-class education. I suppose in the end there is a trade-off between stability, efficiency, and safety versus individual freedom to engage in “creative destruction”, and one has to simply decide which spot on the continuum is most satisfying. Hopping on the bus to Kuala Lumpur, I felt fortunate to have experienced both ends of the spectrum in one lifetime.

 

First Attempt at Python Programming!

Last night I was reading through Hello World!, an introductory programming book loaned to me by a coworker, and decided to give Python a crack. Here’s my first attempt. Just paste it into a text editor and save as ‘lat2dms.py’. Then run it in IDLE GUI (free download) with F5. If you type lat2dms(###) in IDLE it will convert the decimal degree value ‘###’ to degree-minute-second format (four outputs, including N/S to indicate direction). I originally wrote it to output a concatenated string of those values but couldn’t figure out how to include the degree, minute, or second symbols (eg ‘ and ”). My ultimate goal is to use this as a building block for a script that will import a CSV file with geodata  in one format and output a new CSV file with the same data in a different format, suitable to be used with Excel or any compatible geographic information system. I’m about halfway through the loops chapter, so hopefully that will come in handy. This has been a fun exercise and I hope I can continue learning on the side.

#this is a program to convert a decimal latitude value into degrees minutes seconds format
#by Will Townes 25 AUG. 2009
#http://willtownes.wordpress.com

def lat2dms(ilat):

#this conditional defines whether the lat. is north or south
    if ilat>=0:
        direction = 'North'
    else:
        direction = 'South'

    ilat = abs(ilat)

#here we parse the initial, decimal value into degrees minutes and seconds.
    degrees = int(ilat)
    rawminutes = 60*(ilat-degrees)
    minutes = int(rawminutes)
    seconds = int(60*(rawminutes-minutes))

    if ilat > 90:
        print "ERROR- invalid latitude value. Please enter a value between -90 and 90."
    else:
        print "(degrees, minutes, seconds, direction)"
        return degrees, minutes, seconds, direction

 

Hong Kong

21 March 2008. (click here for photos) After finishing my Fulbright period in the Philippines, I spent a month independently traveling around Southeast Asia. My first stop was Hong Kong, where I visited my friend Sonia Siu, who was a Rotary Scholar at Hong Kong University studying their welfare system. My first impression was delight at the efficiency of the train I took from the airport to Central station on Hong Kong Island, and the glistening, modern shopping mall with a free (!) internet cafe in the International Financial Center above the terminus. I later discovered, however, that this was the most expensive possible way I could have taken! I wandered the Blade Runner-esque streets toward Lan Kwai Fong, the popular expatriate hang-out, where I met Sonia and grabbed a cab to HKU. When I mentioned that I had just arrived from the Philippines, I was taken aback when the driver reacted by expressing his fear of “dangerous” Muslims in that country. The next day the air was foggy, and somewhat polluted (from the vast number of factories in nearby Guangdong, China). We joined several local rotarians for a dimsum (dumpling) breakfast that included eel, squid, chicken feet, lotus paste, and many other tasty but unidentifiable Cantonese delicacies. Having consumed a massive amount of green tea, and minimal water to dilute it, my head was spinning! I spent the day riding around on the almost century old trolleys and memorizing Chinese characters. I enjoyed identifying some of the plants in the Conservatory in the Hong Kong Park, and randomly made the acquaintance of an amicable business school professor from Brigham Young University, who cautioned that not all finance professionals strike it rich. In the shadow of the Citigroup tower, an Indian man accosted me. Brandishing a picture of his (apparently levitating) guru, he offered to predict my future. Without waiting for my reply, he did so and immediately offered a chart of how I might repay him (in American or Hong Kong dollars, of course!). When I explained I had no cash, he stormed away angrily. Hong Kong also has an abundance of Filipino workers, many of them house maids. I chuckled upon observing, at city hall, signs in English, Chinese, AND TAGALOG warning would-be picnickers to stay off the grass!
The next day, Letitia, a couchsurfing host and nurse, was gracious enough to take me on the tram ride to Victoria Peak, a promontory behind the city in the center of Hong Kong Island. From the top, we gained an excellent vista of Kowloon and the many ships traversing the narrow strait between that peninsula and our island. As we hiked through the surprisingly lush vegetation down the back (Southwest) side of the mountain. Letitia related her experience working in the hospital during the deadly SARS outbreak, which even claimed the lives of some of her colleagues. The virus apparently came to Hong Kong by a man infected in Guangdong while hunting wild game. In the distance, we could see a large coal fired power plant on a smaller adjacent island, a power source for the bustling metropolis of 7 million people. Later, Letitia introduced me to a crunchy, spicy local variety of seafood, and congee,  a creamy rice porridge that reminded me of grits.
Another interesting experience was joining Sonia’s rotary colleague Brad and others for an Indian meal in the menacingly labyrinthine Chungking Mansions on Kowloon. Brad explained that, while widely acknowledged as the most affordable place to live in the city, it had a history of fires and crime. Most of the residents appeared to be import/export businesspeople from South Asia, the Middle East, and Africa. I was disoriented when I arrived, because I had just caught the last sky tram down to Tung Chung after climbing Lantau Peak (second highest in Hong Kong) earlier that day. Overall, I thoroughly enjoyed Hong Kong and would love to go back. It’s hard to imagine any other cosmopolitan city (it really is the “New York of Asia”) with so much natural beauty in close proximity. On my final day, I rode the ferry to Macau (home of the world’s largest casino, and a former Portuguese colony!) and spent the night in a hostel owned by a Bangladeshi man next to two Chinese Malaysians and a Filipina. As I closed my eyes I knew that I would have colorful dreams after living in such a fascinating, heterogeneous microcosm for a brief but exhilarating five days.

 

Visualization of Frequently Used Words

Check out this cool visualization of the most frequently used words in the blog so far at wordle:

 

Sagada

March 2008. Click here for photos.
During my final days in the Philippines, I traveled with Rissa, Ryan, and Riva to Sagada and Banaue in the Cordillera region of northern Luzon. We took the overnight bus to Banaue (almost 12 hours on a bumpy road) and had breakfast overlooking the famous rice terraces. The ancient indigenous Filipinos constructed these staircase-like irrigated terraces so that they could grow rice even in the extremely steep terrain of the mountains. Interestingly, this is one of the only ancient engineering feats that was accomplished without the use of slave labor (compare this to the Egyptian pyramids).
We then took a Jeepney up the steep dirt road to Bontoc and eventually Sagada. When we got out in this ethereal village, the first thing I noticed was the frequent splotches of orange coloration on the concrete pavement. Ryan explained that this was caused by locals chewing Betel nut, a mild stimulant, and spitting out the juice, which stains the pavement. Our jeepney driver allowed me to sample one from his pouch. He wrapped the nut in a ‘betel leaf’ and added some white powder. I tried to chew it but the bitter taste caused my cheeks to pucker as if I was eating a sour persimmon. I quickly spat it out, with an anguished expression which greatly amused the local passers-by.
Sagada was a wonderful contrast to Manila, with clean air, a very slow pace of life, and relatively safe and predictable foot and vehicle traffic. We enjoyed pancakes for breakfast, swimming in a giant cave, hiking along the spiny Karst ridges, exploring the steep cliffs where local ancestors were buried in hanging coffins, and meeting some of the other travelers. We befriended four German visitors; two were biochemistry and stem cell graduate students. They taught me how to say “I am a beautiful angel” in German: Ich bin eine wunderbare Enggel! I kept repeating it as we walked back to the town from our caving adventure because it was cold and raining and I wanted to keep my mind occupied.
On the long, sleepless return to Manila, I couldn’t help but recognize the parallels between Sagada and Monteverde, Costa Rica, where I spent 5 months in college studying the rain forest. It seemed fitting that my studies of tropical life, and my inspiration to apply for a grant that would send me to the other side of the world, away from everyone and everything I knew and loved, would both begin and conclude in a small town surrounded by cloud forests and cow pastures. I wondered what my friends from Costa Rica, North Carolina, and Washington and Lee were doing back in the Western Hemisphere, and felt for the first time a strong tug homeward.

 

Power Plants and Whale Sharks

March 2008- photos for this post here.

The Bicol Peninsula of Luzon is known for its spicy food, convoluted coastline, and active volcanoes. On my first visit to Bicol in December 2007, fellow fulbrighter Rissa introduced me to her aunt’s coworker, Cam, who offered to show me around the coal-fired power plant where he worked. In March, Cam generously took the time to host me in Mauban, Quezon Province, and explained to me the inner workings of the plant. It was amazing to see how organized, professional, and clean everything was inside the plant. There was a big fence around the whole area, a loading dock where coal from Kalimantan (Indonesian Borneo) is delivered, the furnace and smoke stack itself, and a small village housing the employees. My first impression of the community was that it was almost too perfect, similar to the dharma initiative village in Lost. Everything was running smoothly. Cam even explained to me the prolific, and extremely specific, environmental control measures the power plant employs, many of which go above and beyond the requirements set by the government regulator. I was especially impressed that the company had planted hundreds of trees on their property, and actively defended the stand from timber poaching. In sharp contrast to so many other experiences I had had in the Philippines, this place was actually functional. It reminded me too much of the United States! I was almost experiencing reverse culture shock by the time Cam dropped me off again at the Pagbilao bus terminal.

Whale sharks, the largest fish in the world, have long been associated with Donsol, Sorsogon, my next stop in Bicol. For years, fishermen from this sleepy town cursed the giant butanding for breaking their nets. Then one day a German tourist came and photographed more than a dozen whale sharks in a single day, and before long hordes of foreigners descended on Donsol. Now tourism is a mainstay of the local economy, and a huge shark mural adorns the elementary school wall. I was not disappointed in my own attempt to see these majestic creatures. It was fantastic to swim beside a fish the size of a school bus, even if the sheer number of other tourists in the water made it difficult to avoid getting finned in the nose occasionally. Later, I met up with a South African, an Australian couple, and a beer-drinking local tour guide who professed to be a member of the enigmatic Iglesia ni Cristo religion. They convinced me to postpone my return to Manila so I could join them in visiting a small island off the coast of Masbate, where a waterfall plunges off a cliff directly into the ocean. The S. African guy and I swam under the waterfall, and there were tiny red corals growing under the churning water. It was really fun to be pushed down to the depths by the force of the torrent. The tour guide and the boat captain cooked a fantastic lunch, including grilled liempo (kind of like a pork chop), mangoes, and an excellent marinated fish kebab. I spent my final night in a cheap hotel in Legaspi, and ended up chatting for hours with a gregarious medical supply salesman from Ilocos and the hotel staff, who convincingly pretended to be amazed at my Tagalog skills, and asked to take pictures with me. I never ceased to be amazed by the kind-heartedness of such people. The joy of sharing laughter and fellowship with new friends is the greatest reward for the weary traveler.

 

Personal “Firsts”

Here are a few things I did for the first time ever while I was in the Philippines:
FOOD

• monitor lizard, aka “bayawak” adobo
• balut, the boiled duck embryo
• dinuguan, a congealed blood pudding
• isaw, grilled pig and chicken intestines

RELIGION

• I was invited to be one of three judges at a theological debate on “nature versus nurture” in a Claretian Seminary. I was supposed to represent the “scientific” judge. One of the other judges was an Opus Dei microbiologist and the other was a born-again Christian engineering student. All three of us were friends by the time the debate was over.
• I touched the Black Nazarene in Quiapo.

INSOMNIA/POLITICS

• I once stayed awake for 40 continuous hours soaking up the Manila nightlife. During this period, I walked through a rally intended to overthrow the government on my way to fellow fulbrighter Denver Nicks’ presentation on the government’s proportional representation system and its political ramifications.
• While observing an NGO rally against the Japan Philippines Economic Partnership, I accidentally wandered into the main chamber of the Philippines Senate without an ID
• Experienced walking through the heart of the market district during a coup attempt by a Senator, who, prior to election, had already been jailed once for attempting to overthrow the government. When I panicked and asked my Filipino companion what to do, he said, “no big deal, it happens all the time.”

 

‘Totoy Kano’ visits Taal Volcano

February 25, 2008

(click here for photos from this trip)

“Totoy Kano” is a nickname the Aytas gave me, roughly translating to “American dude”, and whenever I used this alias, people found it hilarious. One example of this occurred when I was out hiking with my friend Happy (yes, that’s her real name!). We were visiting the Taal Volcano, a geological wonder not far from metro Manila. It is considered the world’s largest island in a lake on an island in a lake on an island! In order to get to the crater, you first drive to the edge of Taal Lake (you are already on Luzon Island), take a bangka across the lake to the island in the middle, then climb up to the edge of the crater, where you can see yet another lake with a smaller island inside! The hike was very dusty, due to the large numbers of horses used to transport Taiwanese, Korean, and (to a lesser extent) European tourists up to the top. Happy and I managed the trek on foot and celebrated with a cool buko (young coconut) drink, freshly cracked open by a machete. On the way down, we swapped book recommendations (mine was The Name of the Rose by Umberto Eco). I found out from a local guy that the big lake around the volcano is heavily used to farm Tilapias to be sold in Manila fish markets, an activity not without environmental implications, as the concentration of waste and feed can alter the chemical balance of the lake.
Happy has a pretty cool family (most of whom I got to know later on). Her brother Gino is a hip hop artist known as “Nimbus Nine”, and her sister Twinkle is a designer. Happy herself was active at the time in a fantastic comedy troupe called Silly People’s Improv Theater. Anyone planning a trip to Manila should try to go to one of their shows. They usually perform at places like Mag:Net Cafe.