March 29, 2013
If the Easter Bunny comes to your house this weekend, you may find yourself with a plethora of marshmallows and Peeps. What to do with them all? Aside from simply eating them, cooking with them, or unleashing your artistic side by making dioramas, consider using them….for science!
Marshmallows, it turns out, are must-have pieces of equipment for at-home science experiments. Sure, you can use them test your kids’ self control through the the field of psychology’s notorious marshmallow test and its ever-more complex iterations. But if you’d rather not torture your kids by leaving tantalizingly in reach a marshmallow they’re ordered not to have, consider trying these easy science projects:
Marshmallows in a vacuum
No, not that kind of vacuum, despite the intriguing possibilities conjured by this phrase. You’ll need:
- A glass jar with a lid
- A mechanism to pump some of the air out of the jar
Place a few marshmallows in the jar, seal it, and then pump the air out:
What’s going on? Marshmallows are basically a foam spun out of sugar, water, air, and gelatin. The sugar makes them sweet, the water and sugar combo makes them sticky and the gelatin makes them stretchy. But the air–which actually makes up most of the confection’s volume–makes marshmallows the tastiest way to encapsulate a gas in a solid. As you pump air out of the jar, the air inside the marshmallow expands and the marshmallow puffs up. Release the seal, and the marshmallows return to their normal size.
Congratulations! You’ve just demonstrated Boyle’s Law, which states that when the temperature doesn’t change, that the relationship between pressure (which is decreased by pumping air out of the jar) and volume of any set amount of gas (the marshmallow) is inversely proportional. In other words, decreasing one necessitates an increase of the other.
If you can’t eat ‘em, nuke ‘em!
If you’ve ever roasted a marshmallow over a campfire, you’ll know where this next demonstration is going. You’ll need:
- A microwave
- A microwavable plate
- A standard-sized marshmallow (avoid minis or jumbos; the former will fry and the latter may make an enormous mess!)
Place the marshmallow on one of its flat sides in the center of a plate. Then microwave the marshmallow for, say, 45 seconds on high.
It’s alive! This time, rather than changing the pressure surrounding the marshmallow, you’re changing the temperature. As the microwave bakes the marshmallow, the water in the marshmallow heats up and warms the air. When air becomes hot, it expands, forcing the marshmallow to puff up. The confection’s water also softens the sugars, causing it to ooze, as seen in the video above (created by YouTube user bbbpwns).
The relationship between temperature and volume is representative of Charles’ Law, which holds that any set amount of gas will expand when heated–increasing the temperature of a gas necessitates an increase in the gas’ volume.
Trying this with Peeps makes for a slightly alarming outcome, showcased by YouTube user UBrocks:
If you flashed back to the Stay Puft Marshmallow Man, alas–the monster marshmallow you pulled from your microwave doesn’t last–it will cool and deflate into a glob of ooze. But before it cools completely, the ooze is quite malleable and can be sculpted into shapes. But careful! The marshmallow remnants are like naplam–they’ll stick to you and burn. After it cools a bit, brush some oil on your palms before you mold anything, else your sculpture will stay glued to your hands.
A gooey way to calculate the speed of light
For this demonstration you need a bit of background knowledge as you start out. The speed of a wave can be calculated by multiplying the wavelength (the distance from crest to crest) with the frequency (the number of crest-to-crest cycles that repeat in a stretch of time). Light is a wave, and its speed can be calculated the same way without fancy equipment. You’ll need:
- A microwave with the turntable removed
- A glass casserole dish or baking tray
- Mini marshmallows
- A ruler
- A calculator
Take the baking tray and pack one layer of marshmallows along the bottom, lined up like tiny puffy soldiers. Make sure the turntable is removed from the microwave–this allows microwaves to move through the glass and the marshmallows in a standing wave pattern. Cook for a few minutes on low, watching the marshmallows carefully. With the turntable removed, the microwave doesn’t heat evenly–you’ll notice melted patches forming in your marshmallow field.
As soon as you see a few such patches, remove the dish and measure the distance between two that form a line parallel to the microwave’s door–these mark the locations of highest amplitudes within the standing wave. Multiply this by two to get the full wavelength of the microwaves that passed through your marshmallows (if you look at the geometry of a standing wave, your initial measurement only gave you half the wavelength). Convert this into meters.
Multiplying this result by frequency of the microwave, found in the microwave’s manual or in a label inside the device, gives ~299,000,000 meters per second–roughly speed of light! Catch a video of this here.
July 2, 2012
The Washington, DC area has seen its fair share of destructive storms–we get hurricanes, tornadoes and even the rare snowpocalypse. But on Friday night we got hit with another type of storm–one that I’d never heard of–called a derecho (pronounced ”deh-REY-cho”).
The storm swept through the area late Friday evening, bringing an incredible amount of thunder and lightning, winds up to 80 mph and sheets of rain. By morning, hundreds of trees had been blown down, millions were left without power and several people were dead. Netflix, Pinterest and Instagram had all been taken down by Amazon server outages caused by the storm. The Smithsonian Folklife Festival had to shut down for a day to clean up the mess. We were all left wondering, “what in the world had happened?”
The stifling heat wave that we’d been suffering through, which had stretched from the Midwest through the mid-Atlantic to the Southeastern United States and brought temperatures in excess of 100 degrees Fahrenheit, was to blame for the fast-moving band of thunderstorms. The Capitol Weather Gang explains:
As this stifling air bubbled northward, clashing with the weather front draped from near Chicago to just north of D.C., thunderstorms erupted. They grew in coverage and intensity as they raced southeast, powered by the roaring upper level winds and fueled by the record-setting heat and oppressive humidity in their path.
The coverage and availability of this heat energy was vast, sustaining the storms on their 600 mile northwest to southeast traverse. The storms continually ingested the hot, humid air and expelled it in violent downdrafts – crashing into the ground at high speeds and spreading out, sometimes accelerating further.
Though unfamiliar to those of us here on the East Coast, derechos occur more commonly in the Corn Belt, which runs from Mississippi into the Ohio Valley, but even there they are relatively infrequent. They can wreak their havoc at any time of the year but are most likely to occur during May, June and July. Derechos get their starts in curved bands of thunderstorms called “bow echoes,” which are perhaps better known for their ability to spawn tornadoes. But instead of rotating cells of winds, derechos blow and travel in straight lines.
Derechos have a long history here in the United States. The term “derecho” was coined by University of Iowa physics professor Gustavus Hinrichs in an 1888 paper in the American Meteorological Journal in which he illustrated the path of such a storm that had crossed over Iowa on July 31, 1877. The storm’s straight path across the state gave Hinrichs the inspiration for the storm’s name–”derecho” means “straight” in Spanish. But path alone isn’t quite enough for a storm to qualify as a derecho; wind speeds must also reach a minimum of 57 mph.
Given that derechos are associated with warmer weather, could they become more common as the United States heats up due to climate change? Tom Kines, senior meteorologist at AccuWeather.com, told the Guardian: “If indeed we are seeing global warming, then it will certainly increase the risk of something like this happening again.”
December 22, 2011
You probably don’t pay too much attention to the imagery on the Christmas cards you receive or the paper wrapping your presents. You probably care more about the card’s message or the attractiveness of the gift wrap. And it’s probably just as well, since a new study in the journal Communicating Astronomy With the Public has found that depictions of the Moon on Christmas cards and gift wrap and in children’s Christmas books are often wrong.
Peter Barthel, an astronomer at the University of Groningen in the Netherlands, was spurred to look into this issue after seeing a Unicef Christmas card in 2010 and a popular animated Advent e-calendar that year that both showed an unlikely Moon. The card depicted children decorating a Christmas tree beneath a waning crescent moon (one with its left-hand side lit) while the calendar scene showed people caroling, also under a waning Moon. The problem here is that the waning Moon doesn’t rise until 3 a.m. While it’s not impossible that these scenes could take place in the early morning hours, “it’s unlikely,” Barthel writes.
And so Barthel began to examine Christmas scenes on wrapping paper and cards and in books in both the Netherlands and the United States, two countries that have done much to shape our modern view of Santa Claus and Christmas. He found that 40 percent of the pictures in Dutch Christmas books and 65 percent of the Dutch gift wrap samples incorrectly showed the waning Moon. And this wasn’t a modern problem–six out of nine samples from a collection of older Dutch gift wrap also depicted, wrongly, the waning Moon.
American Christmas artists did better at showing a believable Moon in their images, but simply because they more often draw a full Moon in Christmas scenes. (The full Moon rises at sunset and shines over evening holiday scenes naturally.) That said, Barthel did find examples of incorrect waning Moon scenes. One booklet even showed a full Moon and a waning Moon in the same night.
Should we care? Barthel says yes:
The errors are innocent, somewhat comparable to incorrectly drawn rainbows, with the colour at the inside of the arc. Now watching beautiful phenomena like rainbows and moon crescents is one thing, but understanding them makes them all the lot more interesting. Moreover, understanding leads to knowledge which lasts.
And I don’t think it’s too much to ask for artists, especially ones drawing for children, to pay a little attention to accuracy in something like this. After all, if artists like Vincent Van Gogh and Edvard Munch could take the time to use real moons and stars in their paintings, surely modern artists could as well.
Read more articles about the holidays with our Smithsonian Holiday Guide here
December 8, 2011
On the night of May 22, 1453, the people of Byzantium could see an eerie red shadow cross the Moon. It was a partial eclipse–the Earth had gotten in between the Sun and Moon–and the Byzantines took it as a bad omen. And perhaps they were right–the city of Constantinople fell before the month’s end.
A full lunar eclipse will take place this weekend, visible from Asia, Australia and western North America. But people today don’t view this astronomical event as a worrying sign. Instead, it’s time for science! And you can participate.
The Classroom Astronomer magazine has set up a website, measurethemoon.org, to coordinate observations of the position of the moon in the sky as it passes through our planet’s shadow. And if you’re in the right place, you can measure the distance from the Earth to the Moon.
There are two ways to do this. The first is called the Shadow Method, and it’s the way that the ancient Greeks first measured the distance between the Earth and Moon thousands of years ago. Amy Shira Teitel explains in Universe Today:
Start with the few knowns. We know, as did the Ancient Greeks, that the Moon travels around the Earth at a constant speed—about 29 days per revolution. The diameter of the Earth is also known to be about 12,875 kilometers, or 8,000 miles. By tracking the movement of the Earth’s shadow across the Moon, Greek astronomers found that the Earth’s shadow was roughly 2.5 times the apparent size of the Moon and lasted roughly three hours from the first to last signs of the shadow.
From these measurements, it was simple geometry that allowed Aristarchus (circa 270 B.C.) to determined that the Moon was around 60 Earth radii away (about 386,243 km or 240,000 miles). This is quite close to the currently accepted figure of 60.3 radii.
You can follow Aristarchus’ method in your own backyard if you have a clear view of a Lunar eclipse. Track the movement of the Earth’s shadow on the Moon by drawing the changes and time the eclipse. Use your measurements to determine the Moon’s distance.
The second method, the Lunar Parallax Method, was familiar to the ancient Greeks but they lacked the ability to communicate over the far distances that is necessary to carry this out. Telephones and the Internet make this easily possible now. Two observers at least 2,000 miles apart will have to snap a picture of the Moon at the exact same moment. Because the angle at which the Moon and the stars behind it will be different for each person, the images they snap will be slightly different, particularly the stars in the background. “What your images have given you is a triangle,” Teitel explains. “You know the base (the distance between you and your friend), and you can find the angle at the top (the point of the Moon in this triangle). Simple geometry will give you a value for the distance of the Moon.”
If the people behind measurethemoon.org get enough participants, they’ll be able to compare all the various calculations, determine which method is more accurate and figure out how close two people have to be to get an accurate calculation with the Lunar Parallax Method.
If you’re not up for calculations, there are a few other lunar eclipse science projects you might want to participate in:
- Roger Sinnott of Sky & Telescope is collecting telescopic timings of the the passage of Earth’s shadow across lunar craters (find instructions here) as part of a long-term project to track the unpredictability of the diameter of the shadow.
- John Westfall of the Association of Lunar and Planetary Observers is collecting timings of when the phases of the lunar eclipse begin and end, made with the unaided eye, to calibrate similar observations made in the past when mariners used the Moon to determine longitude.
- Richard Keen of the University of Chicago will collect reports of the Moon’s brightness from amateur astronomers for use in volcano-climate studies.
After reading all this and seeing the picture above, you may be wondering why the Moon in a lunar eclipse turns red, not black. “That red light on the Moon during a lunar eclipse comes from all the sunrises and sunsets around the Earth at the time,” says Robert Naeye, editor in chief of Sky & Telescope. “If you were an astronaut standing on the Moon and looking up, the whole picture would be clear. The Sun would be covered up by a dark Earth that was ringed all around with a thin, brilliant band of sunset- and sunrise-colored light, bright enough to dimly light the lunar landscape around you.”
If, like me, you’ll miss out on this chance to see a lunar eclipse, your next opportunity will come in April 2014.
November 10, 2011
If you’re trying to convince your boss to let you telecommute, you quickly run into a data problem. That is, there isn’t a lot of it. Oh, there are plenty of studies, but many of them are theoretical or anecdotal. What’s really needed is an experiment, with large numbers and a control group, like what is done when researchers test new medicines.
Well, we’ve lucked out, as someone has actually run that experiment, as Slate noted this week. A group of researchers at Stanford University partnered with a large (>12,000 employees) travel agency in China that was founded by a former Stanford Ph.D. student. The company’s chairman was curious about whether instituting a telecommuting policy would work for his employees and what kind of effect it would have. So they used employees in the company’s call center–the people who handled phone inquiries and booked trips–to test the questions (the results haven’t been peer reviewed yet, but they can be seen in this presentation [PDF]).
A call went out for volunteers, and 508 of the 996 employees in the group spoke up. Of those, 255 qualified for the study; they had the right space at home and enough experience at the company to be trusted on their own. The company then held a lottery, and employees with even-number birthdays were allowed to telecommute four out of five shifts a week, and those with odd-number birthdays worked solely out of the office. Like a medical trial, this setup gave the researchers an experimental (telecommuting) group and a control (office) group, which could easily be compared.
What the researchers found should hearten those of us who’d like to telecommute, even once in a while. After a few weeks of the experiment, it was clear that the telecommuters were performing better than their counterparts in the office. They took more calls (it was quieter and there were fewer distractions at home) and worked more hours (they lost less time to late arrivals and sick breaks) and more days (fewer sick days). This translated into greater profits for the company because more calls equaled more sales. The telecommuters were also less likely to quit their jobs, which meant less turnover for the company.
The company considered the experiment so successful that they implemented a wider telecommuting policy. But Slate reports that not everyone in the experiment chose to continue telecommuting; they valued the daily interactions with their workmates more than they disliked their commutes or other downsides of going into the office every day.
Clearly telecommuting is not for everyone. Another factor to consider might be how much a person’s family life interferes with their job, and vice versa. A new study in the Journal of Business and Psychology, for example, found that people who experience a lot of conflict between their family and work priorities suffered more exhaustion when they telecommuted, whether they stuck to traditional work hours or had more flexible schedules. In other words, people who had problems separating the work and personal parts of their lives found it just increased their stress levels when they combined the two at home.
But perhaps I should point out that work-family conflicts aren’t a problem for me, so I’d be delighted to telecommute.