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Over the next few weeks, Paul Gluck, co-author of Physics Project Lab, will be describing how to conduct various different Physics experiments. In his third post, Paul explains how to investigate and experiment with rubber bands…

Rubber bands are unusual objects, and behave in a manner which is counterintuitive. Their properties are reflected in characteristic mechanical, thermal and acoustic phenomena. Such behavior is sufficiently unusual to warrant quantitative investigation in an experimental project.

A well-known phenomenon is the following. When you stretch a rubber band suddenly and immediately touch your lips with it, it feels warm, the rubber band gives off heat.

Unlike usual objects, which expand when heated, a rubber band contracts when you heat it. To see this, suspend a rubber band vertically and attach a weight to it. Measure carefully its stretched length by a ruler placed along it. Now blow hot air on the rubber band from a hair dryer, thus heating it. Measure the new length and ascertain that the band contracted.

The behaviour is also strange when you try to see how the length of a rubber band depends on whether you load or unload it. To see this, suspend a rubber band, affix to its bottom a cup to hold weights, as shown.

Now increase the weights in the cup in measured equal increments, and for each weight measure the length, and the change in length from the unstretched state, of the rubber band by a meter stick laid along it.

For each weight, wait two minutes before the new length measurement Record your results. Now reverse the process: unload the weights one by one, and measure the resulting lengths.

For each amount of weight, will the rubber band have the same length when loading as when unloading? No, the behavior is much more subtle and is shown in the graph, in which one path results when loading, the other when unloading. This effect is known as hysteresis, and is related to energy losses in the band.

What happens to the sound of a plucked rubber band?

Try it: pluck a rubber band while gradually stretching it, thereby increasing the tension in it. In the process the plucking produces a pitch which is practically unchanged. But if you keep the length of a rubber band constant but increase the tension in it somehow, the pitch will change. You can keep the length constant, while changing the tension, as follows: fix one end of the rubber band or strip. Pass the free end over a little pulley, affix a cup to that end to hold weights, then putting increasing amounts of weight into the cup will increase the tension in the rubber band, while keeping its length constant.

Unless you have perfect pitch and can detect small differences in pitch, you may need more sensitive means to detect the variations. One way is to have a tiny microphone nearby that will pick up the sound produced when you pluck the band. This sound is then passed on to a software (on the Web search for ‘free acoustic spectrum analyzer’) which analyzes the sounds and tells what frequencies are present in the plucking sound.

Finally, how does a flat thin rubber strip transmit light? Take a very thin flat rubber strip and start stretching it. Now shine a strong spotlight close to one side of the strip and measure the intensity of the light which is transmitted on to its other side, while the strip is stretched. You would expect that as the strip is stretched it becomes thinner so more light should get through, right? Wrong: for some region of stretching the transmitted light intensity may actually decrease.

If you have access to a physics lab and modern sensors you can set up an apparatus which will allow to explore in depth the whole range of phenomena to greater accuracy.

Have you tried this experiment at home? Tell us how it went to get the chance to win a free copy of the Physics Project Lab book! We’ll pick our favourite descriptions on 9th January.

The post Physics Project Lab: How to investigate the phenomena surrounding rubber bands appeared first on OUPblog.

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So, I think I can safely say that today, I was one hot chick!

Anything over 75 degrees is too hot for me. So let’s just say today’s weather topping off at 109 really ruffled my feathers!

I don’t want to count my chickens before they’re hatched, but IS IT FALL YET?!!

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This week—August 15, to be exact—celebrates the climax of Air Conditioning Appreciation Days, a month-long tribute to the wonderful technology that has made summer heat a little more bearable for millions of people. Census figures tell us that nine out of ten Americans have central air conditioning, or a window unit, or more than one, in our homes; in our cars, it’s nearly universal. Go to any hardware or home goods store and you’ll see a pile of boxes containing no-fuss machines in a whole range of sizes, amazingly affordable, plop-’em-in-the-window-and-plug-’em-in-and-you’re-done. Not only do we appreciate the air conditioner, but we appreciate how easy it is to become air conditioned.

When it comes to cool, we’ve come a long way. But in earlier times, it was nowhere near as simple for ordinary citizens to get summertime comfort.

One of the first cooling contraptions offered to the public showed up around 1865, the brainchild of inventor Azel S. Lyman: Lyman’s Air Purifier. This consisted of a tall, bulky cabinet that formed the headboard of a bed, divided into various levels that held ice to cool the air, unslaked lime to absorb humidity, and charcoal to absorb “minute particles of decomposing animal and vegetable matter” as well as “disgusting gases.” Relying on the principle that hot air rises and cool air sinks, air would (theoretically) enter the cabinet under its own power, rise to encounter the ice, be dried by the lime, purified by the charcoal, and finally ejected—directly onto the pillow of the sleeper—“as pure and exhilarating as was ever breathed upon the heights of Oregon.” Lyman announced this marvel in Scientific American, and in the same issue ran an advertisement looking for salesmen. Somehow the Air Purifier didn’t take off.

More interesting to homeowners was the device that showed up in 1882, the electric fan. Until then, fans were powered by water or steam, usually intended for public buildings rather than homes, and most of them tended to circulate air lazily. But the electric model was quite different, with blades that revolved at 2,000 rpm—“as rapidly as a buzz saw,” observed one wag, and for years they were nicknamed “buzz” fans. They were some of the very first electrically powered appliances available for sale. They were also exorbitant, costing $20 (in modern terms, about $475). But that didn’t stop the era’s big spenders from seizing upon them eagerly. Delighted reviewers of the electric fan claimed that it was “warranted to lower the temperature of a room from ninety-five to sixty degrees in a few minutes” and that its effect was “like going into a cool grove.”

The fan combined with ice around the turn of the century, producing an eight-foot-tall metal object that its inventor called “The NEVO, or Cold Air Stove.” The principle was simple: air entered through a small pipe at the top, was pulled by a fan through the NEVO’s body—which had to be stuffed daily with 250 pounds of ice and salt to provide the cooling—and would then be discharged out an opening at the bottom. “It dries, washes, and purifies the air.” As the NEVO had more in common with a gigantic ice cream freezer than with actual temperature control, and the smallest NEVO cost $80 (nowadays, $1,700) and cost $100 per season (over $2,000) to operate, it didn’t get far.

By this time, a young engineer named Willis Carrier had developed a mechanical system that could actually cool the air and dry it, the Apparatus for Treating Air. But this was machinery of the Giant Economy Size, and used only in factories. In 1914, one wealthy gent asked Carrier to install a system in his new forty-bedroom Minneapolis home, and indeed the system was the same type that “a small factory” would use. Unfortunately, this proud homeowner died before the house was completed, and historians speculate that the machinery was never even turned on.

It wasn’t until 1929 that Frigidaire announced the first home air conditioner, the Frigidaire Room Cooler. This wasn’t in any way a lightweight portable. The Room Cooler consisted of a four-foot-tall metal cabinet, weighing 200 pounds, that had to be connected by pipes to a separate 400-pound compressor (“may be located in the basement, or any convenient location”). And it cost $800, in those days the same as a Pontiac roadster. While newspaper and magazine articles regarded the Room Cooler as a hot-weather miracle, the price (along with the setup requirements) meant that its customers came almost solely from the ranks of the rich, or businesses with cash to burn. Then fate intervened only months after the Room Cooler’s introduction when the stock market crashed, leaving very little cash for anyone to burn. Home air conditioning would have to wait until the country climbed back from the Depression.

Actually, it waited until the end of World War II, when the postwar housing boom prompted brand-new homeowners to fill their houses with the latest comforts. Along with television, air conditioning was at the top of the wish list. And at last, the timing was right; manufacturers were able to offer central cooling, as well as window units, at affordable prices. The compressor in the backyard, or the metal posterior droning out the window, became bona fide status symbols. By 1953, sales topped a million units—and the country never looked back.

Appreciation? Of course. And perhaps, adoration.

The post An appreciation of air conditioning appeared first on OUPblog.

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This week I was asked to create a banner for New England's SCBWI Facebook page. This was an honour and a lot of fun to do. What better than lobster and water on a day that was over 90F .. phew, Maine!

Here is the banner.

View it on Facebook at NESCBWI page

I wanted to keep it fun and lively, so it's one of my digital drawings straight into Photoshop, no sketching. It stops me overthinking and it's a style that is appealing to younger eyes. And older ones too I hope!

Right now I am packing to go to ALA (American Library Conference) in Anaheim, CA. This is my first time at a big library conference and it's exciting. I have two book signings, so if you are going, catch me at Kane Miller (with Anastasia Suen, author of 'All Star Cheerleaders') at 11am Saturday and at Charlesbridge's booth Saturday 2-3pm signing 'Hidden New Jersey'.

I am looking forward to meeting LIBRARIANS and catching up with some industry friends. So please come and say HELLO!

There will be photos ...

Right, back to packing.

Toodles
Hazel

On the bedside table:
A slew of Emily Gravett picture books
'Picture This' and 'What it is' by Lynda Barry - recommend highly.

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By Anthony Scioli

Spring and hope are intertwined in the mind, body, and soul. In spring, nature conspires with biology and psychology to spark the basic needs that underlie hope: attachment, mastery, survival, and spirituality. It is true that hope doesn’t melt away in the summer; it isn’t rendered fallow in autumn nor does it perish in the deep freeze of winter. But none of these other seasons can match the bounty of hope that greets us in the spring. My reflections on hope and the spring season are cast in terms of metaphors.

Mind Metaphors

More than three decades ago, linguist George Lakoff and philosopher Mark Johnson demonstrated how metaphors can reveal the inner structure of private feelings. For example, when we refer to “high hopes,” we are revealing something about the phenomenology of the hope experience, that it is “buoyant,” “uplifting,” even “energizing.”

Metaphors of Hope

My research as well as that of psychologists Shlomo Breznitz and James Averill has identified a number of hope metaphors. Below are the four most striking examples.

Light and Heat

Hope has been compared to light and heat. Karl Menninger called hope the “indispensable flame” of mental health. English writer Martin F. Tupper wrote, “though the breath of disappointment should chill the sanguine heart, speedily it glows again, warmed by the live embers of hope.”

Spring also brings added light and heat, sometimes so suddenly that we speak of a virtual “spring fever.” The first day of spring marks the vernal equinox, a balance of daylight and darkness. In the Northern Hemisphere this amounts to an average increase of three hours of light since the winter solstice, roughly a 20% gain. With increased light come a host of direct and indirect effects that improve mood and engender hope. Most directly, increased serotonin is produced. Serotonin is a major excitatory neurotransmitter in the nervous system, and the target of many antidepressant drugs. Among the indirect effects of spring on mood are increased exercise, and the physically related but psychologically distinct activities of gardening and farming.

Like spring, hope is also a 50-50 proposition. If our odds of achieving a particular outcome fall to less than fifty percent, we tend towards “despair.” If we are more than fifty percent certain of an outcome, we become “optimistic.” When psychologist James Averill and his colleagues surveyed individuals about their chances of realizing various hopes, the average response was fifty percent. For this reason, I believe that some kind of faith, not necessarily the religious type, but something essentially “spiritual,” must be present to ground our hopes.

A Bridge

Hope has been likened to a bridge that can actively transport the individual from darkness to light, from entrapment to liberation, from evil to salvation. 0 Comments on Why spring is the season of hope as of 1/1/1900