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February 28, 2011

"An Experimental Study of Wiffle Ball Aerodynamics"


Published in the American Journal of Physics in December, 2007, the above-titled paper by Jenn Rossman and Andrew Rau will tell you everything you ever wished you had known about what makes a Wiffle ball dance.


Too bad it's decades too late for me to make use of it.

But not for you.


[Figures and tables from the paper appear above and below.]

From Dana Mackenizie's March 2011 Wired magazine story on the ballistics of the Wiffle ball: "The go-to researcher is Jenn Rossman, a mechanical engineer at Lafayette College in Easton, Pennsylvania, who specializes in how fluids, especially blood, circulate. In 2003, she started thinking that Wiffle balls might be more interesting for her students to study than the baseballs she'd been discussing in class."


"Over the past eight years, she and her students have built the world's most advanced Wiffle-ology lab, using wind tunnels and computer models to measure aerodynamics. The key to the ball's unpredictability? Air flowing over the perforated side of the ball is more turbulent, as you'd expect, which pulls it in the direction the holes are facing. But two vortices of air trapped inside push it in the opposite direction. Assuming the ball isn't spinning, external airflow wins at low speeds; the internal vortices dominate at high speeds. At 40-60mph — the speed at which most casual players throw — the two forces are about equal, making it hard to predict which way the ball will break."


"Rossman has figured out how to put all that science to use. Scuffing the ball, she says, disrupts the already turbulent external airflow. Result: the internal vortices become more predominant, which 'can nudge it into that higher regime, where it's more predictable,' Rossman says."


The abstract of the 2007 paper follows.



An experimental study of Wiffle ball aerodynamics

We measure the aerodynamic forces on a Wiffle ball as a function of the Reynolds number and ball orientation. The effects of asymmetric flow outside the ball and flow within the ball are considered, and are both associated with the ball’s tendency to curve without pitcher-imparted spin. The problem of Wiffle ball aerodynamics is an accessible way to introduce topics such as boundary layer separation and transition to turbulence.

February 28, 2011 at 04:01 PM | Permalink | Comments (2) | TrackBack

Ultra-soft felt slipper socks


From the website:


Fully handmade felted slippers made of softest Merino wool.


▫ These slippers feel like a second skin on your feet.

▫ Lightweight — each slipper weighs approximately 100 grams (3.6 oz.).

▫ Not slippery! Soles are covered with natural latex which makes them safe to walk in around the house.

▫ Made from softest Australian Merino wool, they gently massage feet. Your feet will be warm on a cold day and cool on a hot day due to the natural insulating properties of the wool fibers.


▫ 100% handmade. Felt is a natural and renewable material, made of 100% wool, using just hot water and soap — one of the most sustainable processes in textiles.

 ▫ Can be made in any size and color. Please specify your size (length, width of your feet and characteristics like narrow, wide foot, or high instep) on your purchase or contact me beforehand to discuss colors and design.

▫ This item is handmade to order and ships within 14 days of purchase.

▫ Care: Hand wash or mashine wash on wool cycle with mild detergent and cool water.


February 28, 2011 at 03:01 PM | Permalink | Comments (3) | TrackBack

MorphWorld: Hahn-Bin into Grace Jones


The young violinist is simultaneously the darling of the classical music and runway crowds.


February 28, 2011 at 02:01 PM | Permalink | Comments (0) | TrackBack

Side Table — "What you see is not what you see"


From the ever-inventive krew at droog comes this space-saving piece of semi-virtual furniture.

"This cool nightstand is a perfect optical illusion. At first glance, it's an ordinary table. Upon a second glance, it's a wall tattoo with potential."

"Beechwood drawer is perfect for a book, alarm clock or mobile phone."


[via 7Gadgets]

February 28, 2011 at 01:01 PM | Permalink | Comments (0) | TrackBack

Which Chinese province do you live in?


The February 24, 2011 issue of The Economist features the maps above and below, comparing Chinese provinces with countries in terms of GDP, population and exports.

From the captions: "China is now the world’s second-biggest economy, but some of its provinces by themselves would rank fairly high in the global league. Our map shows the nearest equivalent country. For example, Guangdong’s GDP (at market exchange rates) is almost as big as Indonesia's; the output of both Jiangsu and Shandong exceeds Switzerland's."

"What about other economic yardsticks? Guangdong exports abroad as much as South Korea, Jiangsu as much as Taiwan. Shanghai’s GDP per person is as high as Saudi Arabia's (at purchasing-power parity, or PPP), though still well below that in China's special regions of Hong Kong and Macau. At the other extreme, poor Guizhou has an income per head close to that of India. Note that these figures use the same PPP conversion rate for the whole of China, yet prices are likely to be lower in poorer provinces than they are in richer ones, thus slightly reducing regional inequality."

Most interesting.


Interactive version here.


February 28, 2011 at 12:04 PM | Permalink | Comments (1) | TrackBack

Hear Ring


Designed by Gina Hsu.





[via carlovely]

February 28, 2011 at 11:01 AM | Permalink | Comments (2) | TrackBack

Knowtilus — "3 resizable web browsers in 1 on your iPad"


Someone I sent this to emailed me back that this iPad app — just released last week and free, the way we like it — appears to bring us that much closer to the singularity.

I don't know about that but I'll let you read the App Shopper description yourself and then decide; it follows.


Knowtilus for iPad is an innovative web browser that includes a writing tool, text to speech, Twitter & Facebook sharing, RSS reader, sketch tool, translator, dictionary, offline reading, Readability and other useful extensions.

Elegant, versatile and simple, it's the first web browser for iPad with a human-like Talking Virtual Assistant. It can read aloud web pages with high quality voices for American English, British English, Australian English, Canadian French, Italian, German, Portuguese, Chinese, Dutch, Spanish, Turkish, Arabic, Romanian, etc. 28 languages included!

12 Reasons To Love Knowtilus


1. Multi-view: With Knowtilus, navigating the web is a new experience with the new multiple browser views feature. You can see simultaneously 1, 2 or even 3 websites on the screen without switching apps or browser tabs! You can hide/show the tabs and use the full screen mode with the Text editor.

2. Text to Speech: Knowtilus can read aloud any web page or selected text using 27 high quality voices. You can also edit your own text and read it aloud! Great for language learning or listen to online news, RSS feeds, blog posts, etc.

3. Writing Tool: Knowtilus has embedded an elegant, easy to use text editing tool. Write posts, notes, to-do lists, reminders even full articles while surfing the web. You can write your content in plain text, HTML or Markdown syntax. Share content between the web and the writing tool. Very interesting for blogglers, journalists, students, etc

4. Readability: Knowtilus has an add-on that makes reading web pages simpler and more enjoyable. Knowtilus strips the superfluous information ( (Ads, Banners, etc.) ) and shows the main content in a single column of easy-to-read text. You can save that clean content to read it later in offline mode.


5. Social Sharing: You can share any web content very easily via Twitter, Facebook or email. Just select any link, text or image and shared it with other people. You can use simultaneously Twitter and Facebook in different browser views.

6. Offline Library: You can download full articles from websites, PDF documents or even ebooks in plain text or HTML format and read them later even if you don’t have Internet connection. This is very useful when you are in the subway, commuting or areas where your don’t have WIFI or 3G.

7. Find: Search your bookmarks or keywords in Google using directly the URL bar. Easily find and highlight specific words and phrases on large web pages with the “search on page” feature. Select words on the web page and find quickly the meaning on Dictionary or Wikipedia.

8. Virtual Assistant: Knowtilus is the first web browser that uses an animated talking avatar to read aloud content and interact with the user.


9. Translator Tool: Translate any web page from practically any language to Italian, Spanish, French, German, Portuguese, Dutch, Chinese, etc. More than 20 languages! You can also translate a web page and read it aloud using TTS.

10. Visual Bookmarks: It has never being easier to organize your bookmarks. Drag and drop screenshots of your favorites to rearrange them. Search your favorites visually or using the integrated bookmarks search engine.

11. RSS reader: Read your RSS channels like a web page and organize them as visual bookmarks. Even the Avatar can read aloud the news from your favorite RSS while you are driving in the car!

12. Sketches: Doodle with your finger directly over web pages, create simple sketches and share them via email or your Photos library. Highlight parts of the web text with different colors.



[via Richard Kashdan, who knows quantum foam from that atop his espresso]

February 28, 2011 at 10:08 AM | Permalink | Comments (3) | TrackBack

Pangolin Backpack


From the website:


Urban backpack handmade from recycled inner tubes of truck attached to each other by a wing nut.

The design of this backpack is inventive and striking — by using overlapping sliding parts it seems like a pangolin.


Large capacity with pockets for small notebooks, pens, MP3 and cell phone, with double-adjustable back straps and handle.

Equipped with a convenient transit for earphones to your MP3 player, iPod or phone.

Three-button magnetic closure with durable rip-stop lining.

Anatomically-shaped to sit pleasantly on your back.




February 28, 2011 at 09:24 AM | Permalink | Comments (3) | TrackBack

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