The geometry of basketball

In the 1990s, I heard an early version of Jim Faller's "The Physics of Basketball" talk. I wish he would post a version of the talk on the web because it really changed the way I see ball sports.

Q: When does a basketball go through the hoop?
A: When the ball is smaller than the hoop.

That can sound nonsensical. A NBA regulation ball is about 9" in diameter and the hoop is 18" in diameter. If the ball is always smaller than the hoop, why doesn't it go in every time?

The hoop does NOT appear circular to the ball as it travels through the hoop.

I drew the schematic for a ball passing through a hoop perpendicular to the plane of the hoop, 90°; and 60°, 45°, 30°, 15° to illustrate.

The ball is easily smaller than the hoop when directed straight downward--like when slam dunking. But, if you are shooting a basket from the court, the size of the hoop depends on the angle of approach of the ball. At around 30°, the ball and the rim are roughly the same size.

This simplification ignores spin, velocity, the backboard and the energy dissipation capacity of the rim. That's why I titled this post, "the geometry of basketball" instead of "the physics of basketball".

But, as soon as Jim mentioned the size thing, I saw a picture of the rim as a separatrix between the scoring and non-scoring regions in my mind. And then I understood the importance of standardizing the materials and flex of the rims and the backboard, and why a player should shoot from as high a vantage point as they can (and still do it accurately).

Then I lost track of the next 10 minutes of the talk as I started applying this to volleyball approaches. My HS volleyball coach was soooo right about approaching from outside the court. Leave a comment if you want me to draw diagrams of how your VB spiking approach determines your collisional cross-section with the set.

Aside:
This post was motivated by Lin-mania. As I mentioned here:

In high school, I worked harder and longer on competitive sports than academics. This was a poor use of my time as Caltech was the only school interested in me athletically. However, I doubted their sincerity; I thought they were secretly interested in my math skills. I ended up at a division I school where the coaches told me not to even bother trying out.

I'm a big believer in practice. Yes, some people are more intrinsically gifted than others. But, all people can improve with practice. For the most part, school wasn't challenging for me until college (with the exception of a few HS classes). So I found something that was hard for me, sports, and worked very, very hard at it until I became good.

Over time, people started calling me a "natural" athlete. Nothing could be further from the truth. It took practice, good coaching, and development of awareness.

I don't think it had anything to do with my Taiwanese-American heritage, or the Japanese and African-American ethnicities of my coaches. They both taught me the importance of drills, conditioning and analyzing the game to see what was effective and what was not. Those were good lessons when the schoolwork became tougher.

Don't miss the SBQG Quilt Show

If you are in the SoCal area, consider yourself invited to the South Bay Quilters' Guild 2012 Quilt show. It will be held in the Torrance Cultural Arts Center February 18-19, 2012. Even if you can't attend, consider buying a raffle ticket to win our gorgeous 2012 opportunity quilt, Floral Fantasy.

Members' quilts will be on view. In addition to the raffle quilt, there will be dozens of smaller auction quilts. The proceeds all go towards our philanthropic activities.

Consider combining your visit with sight-seeing and/or shopping in Torrance. Torrance has so much cachet in Tokyo, this t-shirt is sold out in all but one size.

Actually, this is not completely tongue in cheek. Torrance-Gardena is home to the largest Japanese-American community in the US and the town has a distinctly Pacific Rim flavor. You can get food and goods in Torrance that isn't generally available outside of Japan. Add the beach and surf culture and more Japanese kids have heard of Torrance than kids that live as few as 50 miles away.

We once hosted an international scientist of Japanese descent at work. We asked him what he wanted to see. He took out a map and said, "I understand you are very close to Torrance."

Natasha Ribbed Cable

I'm a bit embarrassed to show a cashmere-blend sweater after the planetary cost of cashmere rant. But it was pre-consumer waste mill overstock purchased from ColourMart. I used the Natasha Ribbed Cable pattern from Adrienne Vittadini's Fall 2003 pattern booklet.
Because this yarn has a different gauge than Natasha, I cast on the number of stitches for a larger size and knit one extra repeat for the sleeves. In retrospect, I wish I had knit two extra repeats for the sleeve and one extra repeat in the body. Oh, well. It is still wearable and I love it.

Remember in pre-consumer waste sewing when I showed pictures from Vogue's Maine Attraction feature last June? I was inspired by the Brunello Cucinelli cable-knit cashmere sweater, $1,720.
I wasn't able to visit the NYC store in person and I didn't see it sold online. But I did see something similar, made from a "cashmere blend" yarn. Mine is a cotton and cashmere blend (perhaps 50/50 but Colourmart isn't sure). My burn test says that there was significant protein content so that sounds about right.
The sweater is symmetrical front to back so I can rotate which way I wear it to minimize wear on the elbows. It is rarely cold enough in LA to wear this, so I anticipate this sweater lasting a lifetime.
The schematic shows how the pieces were shaped.
The sweater weighs 450 grams and the yarn is sold on 150 gram cones.

Colourmart sells mill overstock yarns, which are slightly different from hand-knitting yarns. The yarn feels oily because it is oiled for machine knitting. You knit a swatch and then wash it before determining your gauge. I had to get used to knitting something that looks loose, and then washing it to make the yarn "bloom." So, if you are making something where gauge matters, then make sure you have a little bit extra for swatching.

At $24 per cone, shipping to the US included, you can make your own cabled cashmere blend sweater for a lot less than purchasing it ready-made. You also get a custom fit and the enjoyment of the super-soft (and lightly oiled) yarn winding through your hands for 30-50 hours. Or, you can pay me $1720 to knit you one.

Raveled here.

Valentine Prezzies

Bad Dad and I spent Valentine's day apart. But look what he got me.

Actually, I bought myself the orchids while shopping at Trader Joe's on Sunday and he suggested that they would make an appropriate gift.

I spent the entire day running errands and cooking in preparation for a stint as a single mom. He spent the time clearing up the DVR and his Netflix queue, and spending time alone with his daughter.

Iris told me that they bought the Ferrero Rocher on their walk, but she was upset that he bought the chocolates that I liked instead of the ones she liked. To add insult to injury, he admonished her NOT to eat any before presenting them to me on the morning of Feb 14.

So far, she's eaten four to my one at 73 empty calories a pop. I try to tell her to enjoy a bite at a time, to get the most bang for the calorie. Does that reasoning work on your children?

* An orchid collector told me that you can often score bargains on unusual varieties of orchids at Trader Joe's during major flower-giving holidays. TJ's retail price for the unusual varieties are the same as for the standard ones they sell year-round. But they are delivered to TJ's only when the grower mis-estimates holiday demand and must ship the rarer ones to fulfill the orders. Orchid collectors are known to troll (several!) TJ's first thing in the morning right before peak demand holidays. I found these on Feb 12. There were more unusual varieties there, but I practiced restraint.

Use what you have compostables bin

Redondo Beach residents received new green (compostables) bins last week!

Note that we are allowed, for the first time, to put kitchen waste in with the yard waste.

Bad Dad was not enthused, saying that getting another bin for the kitchen would be a pain. I beg to differ. I went to the garage and took out this bin and matching lid.

The city does not allow plastic bags in the green bin. So I lined it with a brown paper bag.

The city passes out free bins, but only during my work hours.

Free Residential Food Scrap Container
To help you set-up a collection system for the new Curbside Compost Collection Program, the City of Redondo Beach Public Works Department is distributing kitchen counter-top collection containers at no charge. Simply come by the Corporate Yard at 531 N. Gertruda Ave., Redondo Beach between the hours of 9:00 a.m. - 4:00 p.m. Monday - Friday to pick up your container.

Should those hours be inconvenient for you, too, try a local restaurant. My kitchen compostables bin came from Rice Things, a favorite neighborhood restaurant for Japanese comfort food. They buy soy sauce in these containers. If you are a regular there, ask them to save you a bin.

(A neighbor says she buys cat litter from Costco in similar lidded bins.)

When our old trash can broke, I bought a new one and repurposed the cracked shell of the old one to collect our commingled recyclables. I downloaded a recycling symbol graphic from wikipedia, printed it out and taped it to the old bin.

I once read a discussion thread on Apartment Therapy about which is "the best" compost bin. One made of sustainably harvested bamboo? Or recycled resin?

The greenest thing is to use what you already have.

* This is cross-posted on the Adams School CSA blog. Pennamite and I blog about all things CSA-related there. Come visit us there and join our CSA program! The first strawberries of the season have appeared in our boxes. I've already extolled the virtues of local winter strawberries. True winter strawberries are rarely found at supermarkets. Sign up now so you don't miss out.

Wackadoodles, represent!

I read on Officials Say the Darndest Things that Ohio Gov. John Kasich, in his 2012 State of the State address, said:

A year ago, Ohio ranked 48th in job creation. We trailed only Michigan and California in lost jobs-Michigan, the home of the auto industry that was devastated and California, of course, filled by a bunch of wackadoodles.

I had to post a picture of a wackadoodle family (wearing tie-dye!) in response.

I would like to post a few facts about California. We have a significant automobile industry; one report estimates that California ranks 5th among the 50 states in automobile industry employment. We were hurt along with Michigan and the other automobile-producing states.

California is also a manufacturing powerhouse and that sector of our economy has suffered along with the rest of the US manufacturing base.

Our construction sector suffered from overbuilding and the inevitable collapse. That was self-inflicted and we accept the blame for that.

I would like to ask the CEOs of Ohio why, when my Ohio-built washer finally broke, I was unable to replace it with another Ohio-built one? Why had their CEOs decided to shut down the Ohio plants and move the jobs out of the country? I would have plunked down California-earned money to purchase an Ohio product, if they still produced it.

Our nation faces serious problems, and name-calling is not going to help us solve them.

Also in the speech, he said:

In the 21st century, you've got to move at the speed of the marketplace. And so we created JobsOhio. It's beginning to bear fruit in our state already and I'm so excited. Mark, thanks for coming from California. Now he is an Ohio resident. Who knows what we'll see next, right? It's amazing.

We are one nation and people migrate between the states. I have a friend who moved here from Ohio. Why make political hay about it? If you must, see the links below.

Now he's being facetious--I hope.

So we have to devise a strategy, and we're in the process of devising a strategy right now, where we can have a lot of foreign trade efforts and that's foreign trade to places like California and the State of Washington.

Addendum: Due to the timing of this speech, I now believe this is a reference to gay marriage. This is a display of bigotry and not humor.

Recommended reading:

• The Economist on the extent and causes of out-migration from California
• The Center on Budget and Policy Priorities takes a look at the actual data and concurs with the Economist:

  The migration that’s occurring is much more likely to be driven by cheaper housing than by lower taxes. A family might be able to cut its taxes by a few percentage points by moving from one state to another, but housing costs are far more variable. The difference between housing costs in two different states is often many times greater than the difference in taxes. So what might look like migration in search of lower taxes is really often migration for cheaper housing.

Study after study have shown that highly-educated Americans migrate into California for job opportunities and lower-educated ones migrate out of California for cheaper housing. That's not a record to be proud or ashamed of.

I am currently listening to Kevin Starr's whirlwind history of California. Everything transports me to memories about my California. I went to school with people with last names like Castro and Magellan. When I remade a shoebox into Mission San Jose, I never dreamed that I would someday serve as a bridesmaid there (or that the priest would officiate while wearing Birkenstocks).

When I left home to attend the University of California's flagship university, I didn't imagine that I would earn an Mrs to another child of immigrants. But here we are, a California wackadoodle family and proud of it!

Tablecloth Origami

I've wanted to make my own tablecloth skirt ever since Shams posted her online tablecloth skirt tutorial. I made mine a little differently.

I cut one giant 60" square of shot taffeta (brown threads in one direction, blue in the other) by folding the 2 yard piece along a diagonal on the floor. I trimmed away the excess the way I tore off the rectangle when making origami from office paper.

I then folded along the diagonal again and pinned the folds together so that they don't shift and moved the bundle over to my cutting table. I used a compass to draw a 5.25" radius circle and then cut along the pencil mark. I also used my ruler and rotary cutter to chop off 9" squares at the ends. (They look like triangles because of the way they are folded, but they are squares.)

I pinned two of the trimmed corners ready for seaming. I had to unfold and refold the fabric to pin the other two corners. I used French seams on the corners because the acetate shot taffeta was really ravelly.

A fortuitous meeting with Maggie, a cutter on the ground (pricey) floor of Britex led me to cut my circle SMALLER than my hip. Maggie was wearing a black silk taffeta tablecloth skirt with a grosgrain ribbon waist and no zipper or elastic. To put it on, she simply shimmied into it from the top and let it ride low on her waist.

Shams' hips are smaller than her shoulders so she pulls her skirts up. My shoulders are smaller than my hips so I can cut a smaller circle if I pull the skirt down.

I then applied a 35" tunnel elastic waistband with a 27" elastic band. (The 10.5" diameter opening with 3/8" seam allowances made the skirt opening too wide. In retrospect, I could have gotten away with a 10" opening.)

I washed the taffeta, which softened the fabric considerably. I don't know if the lack of edge seams in my skirt also contribute to the corner collapse disorder or if it is solely due to the limpness of the fabric.

The blue tank sweater brings out the blue in the taffeta.

Baby Dashiki

I really don't want to start a flame war about whether we should set aside the shortest month of the year for black history month or if we should teach an inclusive and more complete history year round*.

But, Baby X's mom asked for a baby dashiki for February. And who can say no to this face?

This is the most adorable thing I have sewn since Iris was a baby. Could you ask for a better model/recipient?

• Pattern: self-drafted based on the 2T T-shirt pattern from Kwik Sew's Sewing for Toddlers
• Fabric: 2/3 of a yard of African print cotton from SAS
• Notions: scraps of interfacing and a little bit of black thread
• Construction: flat-felled seams at the shoulder, sleeves and sides (kids are very sensitive to scratchy seams)
  

I want to share a link I found via Kottke.
Letters of Note: To My Old Master

In August of 1865, a Colonel P.H. Anderson of Big Spring, Tennessee, wrote to his former slave, Jourdon Anderson, and requested that he come back to work on his farm. Jourdon — who, since being emancipated, had moved to Ohio, found paid work, and was now supporting his family — responded spectacularly by way of the letter seen below (a letter which, according to newspapers at the time, he dictated).

Many have quoted the paragraph below.

As to my freedom, which you say I can have, there is nothing to be gained on that score, as I got my free papers in 1864 from the Provost-Marshal-General of the Department of Nashville. Mandy says she would be afraid to go back without some proof that you were disposed to treat us justly and kindly; and we have concluded to test your sincerity by asking you to send us our wages for the time we served you. This will make us forget and forgive old scores, and rely on your justice and friendship in the future. I served you faithfully for thirty-two years, and Mandy twenty years. At twenty-five dollars a month for me, and two dollars a week for Mandy, our earnings would amount to eleven thousand six hundred and eighty dollars.

But no one has mentioned the inherent sexism in it. Jourdan Anderson, a freed slave, takes it for granted that his wife's labor should be valued so much less than his own labor.

Does she work less hard? I doubt it.

He simply does not question a system where women's work is worth less than men's.

Just as his former master does not question a system where a white man can own the labor of a black man.

* No, I don't want a Women's history month, thankyouverymuch.