patrick honner

Math teacher in Brooklyn, New York

3-D Printing

3d PrinterThe NYT has an interesting article about the increased use of 3D printers in commercial applications.  Nowadays, companies are using the technology to build custom furniture, low-cost prosthetic limbs, and even housing components.

Basically, the geometry of the object is laid-out in software (like Autodesk), and the “printer” then translates the design into reality by extruding layers of hot plastic, one after another, building the object up essentially by printing one cross section at a time.

It seems that the process is becoming more commonplace and less expensive, opening the door for a wider array of commercial uses.  I’ve seen students using this technology, and it is a pretty remarkable advance.  I believe you can even have a custom-designed plastic guitar built! 

By patrick honner, ago

3-D Illusion Application

child in streetThis is a clever (and creepy) application of optical illusions–a painting, drawn on the pavement, that appears to on-coming drivers as a child playing in the middle of the street.

http://reviews.cnet.com/8301-13746_7-20016169-48.html

The purpose of this, presumably, is to catch the attention of drivers so that they will slow down.

The illusion is strikingly effective, and by watching the video you can see how long the image on the ground is.  I wonder if the painting is equally stretched out at all points–is it just a dilation of a normal drawing?–or is it more of a distorted projection–like Greenland on a flat map?  That is, is the head of the painting five-times normal size, while the shoes of the painting are twice normal size?  My gut feeling is that the painting needs to be distorted like that, but I’m not really sure.

Now, whether this strategy will prevent accidents or actually cause more accidents remains to be seen.

By patrick honner, ago

Lobster-nomics

lobster pricesOne of the benefits of travelling around New England is enjoying lobster in its many forms:  steamed, on a roll, in a bisque, biting your toe.  But while shopping at a fishmonger one evening, I was somewhat baffled to see a sign like the one at the right.  It seems that the price per pound for lobster varies depending on the lobster’s size!

Why is this?  Why should a larger lobster cost more per pound than a smaller lobster?  Large or small, apples are still $1.69 per pound; the same goes for onions, chicken, and most other things.

What’s different about lobsters?  My assumption is that, in a lobster, the ratio of meat to non-meat (shell, antennae, veins, etc) is constant, that is, the same for any size lobster.  Thus, since you are paying for meat, you should then pay the same price per pound for any lobster.  But maybe that’s not the case.  Maybe in a small, one pound lobster, there is, say, 8 oz of meat and 8 oz of shell, but in a lobster twice the size, there is 20 oz of meat and 12 oz of shell.

lobsters

I guess I assumed that the geometry of the lobster is essentially the same regardless of the size; in other words, that all lobsters are geometrically similar.  Thus, the price-per-pound should be lobster-independent.  But maybe I’m wrong.  Is it really the case that, as lobster size increases, the amount of meat and the amount of non-meat increase at different rates?

Anyone have any other theories?

By patrick honner, ago
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