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physics charts

National Museum of American History

Popular Physics

National Museum of American History

Physics demonstration equipment

National Museum of American History

Book, School Physics

National Museum of American History
Elroy M. Avery (1844-1935) was a Michigan native, Civil War veteran, and longtime teacher and scientific lecturer. His Elements of Natural Philosophy, first published in 1878, sold well for years. He also wrote textbooks onchemistry and works on American history. By the 1890s, the term "natural philosophy" had been displaced by "physics," and classroom demonstrations gave way to student experimentation. These trends are reflected in this volume, first published in 1895 with a second printing in 1896. The page facing the inside of the front cover is marked: Jacob M. Schmeltzer (/) Aug 30 1899 (/) Mantino High School (/) October 9, 1899. In this copy of the book, some papers with notes are inserted in the inside front cover. A decorative bookmark is included.

Crash Test Physics

SI Center for Learning and Digital Access
Teacher-created lesson in which students design and test a "CO2-powered balsawood dragster," using prior knowledge of kinematics. The object is to keep an egg unbroken in a crash.

Dynamic Cart for PSSC Physics

National Museum of American History
This wooden cart was designed to show the relation between a force exerted on an object and the velocity of that object. It was simple and inexpensive, made from short pieces of 2" x 4" and three roller skate wheels. This example was made by Grisell and Kaiel, students at Benson Polytechnic High School in Portland, Oregon, in the early 1960s.

The Physics of Flocking

Smithsonian Magazine

Spectra Physics / Perkin Elmer model 110 laser

National Museum of American History

The Physics of Eating Candy

Smithsonian Magazine

Countdown to the Physics Nobel!

Smithsonian Magazine
Use #physnobel on Twitter to submit your questions. The 2014 Nobel Prize in Physics will be announced on Tuesday, October 7. Join guests Charles Day of Physics Today, Andrew Grant of Science News, Jennifer Ouellette of Cocktail Party Physics and Amanda Yoho of Starts With A Bang! as they discuss predictions for possible winners. Who are the best contenders, and who are the potential "dark horse" candidates? Which major physics finds of this year might stand a shot at a win in the future? Victoria Jaggard and Helen Thompson of will be your hosts for the event. Tune in on October 2, and submit your questions on Twitter. Charles Day is the Online Editor for Physics Today magazine. Follow him on Twitter @CSRDay Andrew Grant is the physics reporter for Science News magazine. Follow him on Twitter @sci_grant Jennifer Ouellette is a science writer and blogger at Cocktail Party Physics. Follow her on Twitter @JenLucPiquant Amanda Yoho is a graduate student in theoretical and computational cosmology at Case Western Reserve University and a blogger at Starts With A Bang! Follow her on Twitter @mandaYoho Victoria Jaggard is the science editor for Follow her on Twitter @vmjaggard99 Helen Thompson is a science reporter for Follow her on Twitter @wwrfd

Test, High School Examination Physics

National Museum of American History
This printed examination is entitled “High School Examination Physics.” It also is marked: Thursday, January 23, 1930 - 1.15 to 4.15 p.m. only. Where it was given is unclear. The test was found inside Myer’s copy of Joseph Ray’s Ray’s Algebra (1979.3064.01).

The Physics of Seat Belts

Smithsonian Channel
Until 1966, car seat belts only crossed over a passenger's lap. All that changed when a VIP dummy got behind the wheel and into the history books. From: CRASH TEST HEROES: THE DUMMY REVOLUTION

Tyndall Gift to U.S. to Promote Physics

Smithsonian Archives - History Div
Image of John Tyndall, Irish Physicist. Smithsonian Institution Archives negative number SIA2012-3535.

Annual Report of the Smithsonian Institution for the year 1885, p. 24-25

Annual Report of the Smithsonian Institution for the year 1872, p. 104-106

Professor John Tyndall of the Royal Institution of Great Britain deeds the proceeds of a lecture series, totaling $13,033, to the United States for promoting science in this country, especially in the department of physics. Secretary Joseph Henry participates in directing the spending of this fund.

Spectra Physics model 844 power supply for laser level

National Museum of American History

How Physics Keeps Figure Skaters Gracefully Aloft

Smithsonian Magazine
Every twist, turn and jump relies on a mastery of complex physical forces

Harvard Project Physics Circular Slide Rule

National Museum of American History
The slide rule is a device to assist in multiplication, division and other mathematical operations. Invented in the 1600s, it became popular in American science and engineering in the 1890s. By the 1930s, slide rule use was taught in high schools.

From 1962 until 1972, Harvard University faculty cooperated with others in developing a humanistically oriented high school physics course that might attract more students to the subject. Staff developed not only textbooks, handbooks, transparencies and film loops but this extremely simple and inexpensive plastic slide rule.

The instrument has two circular logarithmic scales for multiplication and division (most elementary slide rules also had scales for taking squares and square roots). There also are linear scales of inches and centimeters.

A stylized bubble chamber image, the logo of Project Physics, appears over the rule. The slide rule was designed so that "Harvard Project Physics" showed just over the shirt pocket of a boy carrying it. This design may reflect the fact that there were no female undergraduates at Harvard College at the time. Not long after this slide rule was made, inexpensive pocket calculators displaced the slide rule.

The Terrifying Physics of WWII Dive Bombing

Smithsonian Channel
The act of dive bombing during World War II was a death defying trial of skill and nerve. You aimed your plane down, four miles above the ocean, and plummeted at speeds of up to 275 miles per hour. From the Show: Battle of Midway

Low-Frequency Torsion Oscillators In Gravitational Physics

Smithsonian Astrophysical Observatory
Eric Adelberger, University of Washington, during the workshop "Optomechanics and Macroscopic Cooling", held February 7-9, 2011at The Institute for Theoretical, Atomic and Molecular and Optical Physics (ITAMP) in Cambridge, Massachusetts. Organized by Pierre Meystre, Arizona, Nergis Mavalvala, MIT, Dan Stamper-Kurn, UC-Berkeley. © Harvard University and Eric Adelberger The text and images on ITAMP's YouTube channel are intended for public access and educational use. This material is owned or held by the President and Fellows of Harvard College. It is being provided solely for the purpose of teaching or individual research or enrichment. Any other use, including commercial reuse, mounting on other systems, or other forms of redistribution requires permission. ITAMP is supported through grants by the National Science Foundation Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s).

Chocolate Fountains are Great for Physics Lessons

Smithsonian Magazine

Chocolate fountains are mesmerizing. And anything that looks that beautiful and can cover ordinary food into chocolaty-covered goodness is a contender for one of humanity’s greatest accomplishments. But as it turns out, chocolate fountains are also valuable tools for exploring the physics of liquids.

In a new paper published in the European Journal of Physics, scientists at the University College London examined why sheets of molten chocolate slope inward as they roll down a fountain instead of splashing straight down. Though a seemingly frivolous goal, chocolate fountains are actually great tools for explaining the complex physics behind how some fluids move, Mary Beth Griggs writes for Popular Science.

Like molten lava, ketchup and oobleck, liquid chocolate is a non-Newtonian fluid that flows differently than substances like water and some kinds of motor oil. Many of these can be fun play with (except maybe for lava), but understanding how these fluids move can be challenging for young physicists.

"Apart from the fact that they’re super cool and delicious, from a scientific perspective, chocolate fountains provide a really nice introduction to non-Newtonian fluids," study co-author Adam Townsend, a Ph.D student at the University College London, tells Rachel Feltman for the Washington Post. In one handy device, a chocolate fountains forces the melted chocolate through multiple different conditions. 

Chocolate fountains work by pumping liquid chocolate up to the top of the structure, where it drips over a dome and then cascades in a sheet to the next dome. In the first step, pressure forces the chocolate up against gravity; in the second step, the chocolate thins out as it flows over a solid object (the dome). In the final step, instead of pouring over the dome’s edge, surface tension causes the chocolate to tuck underneath the dome and then drip down in a sheet.

"It's serious maths applied to a fun problem," Townsend says in a statement. "I've been talking about it at mathematics enrichment events around London for the last few years. If I can convince just one person that maths is more than Pythagoras' Theorem, I'll have succeeded. Of course, the same mathematics has a wide use in many other important industries - but none of them are quite as tasty as chocolate."

Scientific achievements sometimes come at a price—between the study and his lecture demonstrations, Townsend believes he has bought more than 100 pounds of chocolate. But luckily not all of that chocolate went to waste, as hungry students were often happy to help get rid of the sweets once his lecture finished.

"We want them to know that math is in places you don’t expect, it’s interesting, it’s worthwhile to study it," Townsend tells Feltman. "And it’s a nice thing, having a chocolate fountain at a lecture, because they come up afterwards wanting to eat some—and then they ask questions."

Aspen Institute for Humanistic Studies Physics Division

Cooper Hewitt, Smithsonian Design Museum
Aspen Institute for Humanistic Studies letterhead printed in blue on white paper. A specialized departmental version for the physics division. A blue rectangular border frames the page, excluding the white vertical margin at left containing an address printed in blue at top: P.O. Box 219 / Aspen, Colorado. The Aspen Institute logo—a blue Aspen leaf containing a white male figure inside—also appears in the margin at left at the bottom of the page. Printed within the blue border, along the top: ASPEN INSTITUTE FOR HUMANISTIC STUDIES PHYSICS DIVISION.

The Physics of Cheating in Baseball

Smithsonian Magazine

Cheating in sports might be as old as the race between the tortoise and the hare. But not all trickery actually works, especially in baseball.

A corked bat can hit the ball farther, right? That’s a myth, say physicists studying the national pastime. And can making a baseball moister really thwart a slugger from putting one in the bleachers? Well, maybe—depending on how hot it is outside.

To separate fact from fiction, four scientists from three universities spent days firing baseballs at bats. The results are published in “Corked Bats, Juiced Balls, and Humidors: The Physics of Cheating in Baseball” in the June issue of the American Journal of Physics.

To Cork or Not to Cork

In June 2003, Chicago Cubs slugger Sammy Sosa was caught using an illegal corked bat—hardly the first time it’s happened in the Major Leagues. A corked bat is one in which a cavity is drilled out of the barrel and filled with a lightweight material such as cork.

It was scandalous…but does it work? That’s the question that intrigued Alan Nathan, a professor emeritus of physics at the University of Illinois (and a die-hard Red Sox fan). “There was some anecdotal information from players that there’s something like a ‘trampoline effect’ when the ball bounces off a corked bat,” says Nathan, one of the authors of the new study. So the researchers hollowed out a bat, stuffed it with bits of cork and fired a ball at the bat from a cannon. If anything, the ball came off the corked bat with a slower speed than off a normal bat. Less velocity means a shorter hit. Their conclusion: the trampoline effect was bogus.

But there was another way corking might work: a corked bat is a few ounces lighter than an unadulterated one, and a lighter bat means a batter can swing faster, which means he can generate more force and hit the ball farther. Right?

Not quite, as it turns out.

A batter indeed can swing a lighter bat faster, but a lighter bat has less inertia. So there’s a trade-off, says Lloyd Smith, an associate professor of engineering at Washington State University and a co-author on the paper. By once again firing a ball at a bat at WSU’s Sports Science Laboratory, the researchers found that a heavier bat still hit the ball harder (and therefore farther) than a lighter, corked bat. “Corking will not help you hit the ball farther,” says Smith.

“That’s not to say that baseball players are dumb,” Smith is quick to add. Players may have another reason to cork their bats: to make the bats lighter so players can, in baseball argot, “get around on a pitch” quicker, allowing them to wait a split second longer before swinging, which gives them more time to judge a ball’s path and to make adjustments during the swing. “So, while corking may not allow a batter to hit the ball farther, it may well allow a batter to hit the ball solidly more often,” the researchers write.

Smith summarizes it this way: “If your goal is to hit more home runs, you should have a heavy bat. If your goal is to have a higher batting average, you should have a lighter bat.”

Keith Koenig, a professor of aerospace engineering at Mississippi State University and a fellow baseball researcher, trusts the paper’s results but cautions that a bat-swinging machine can never fully predict what might actually happen out on the diamond when real batters swing bats. “If we allow corked bats in the Major Leagues, would there be more home runs?” Koenig muses. “That’s the kind of question that can’t be answered just from lab tests.”

Image by Charles Cherney KRT / Newscom. In June 2003, Chicago Cubs slugger Sammy Sosa was caught using an illegal corked bat—hardly the first time it's happened in the Major Leagues. (original image)

Image by Matt A. Brown / NewSport / Corbis. Sosa was ejected from the game for using a corked bat and Major League Baseball suspended him for eight games. (original image)

Image by Ed Wolfstein / Icon SMI 756 / Ed Wolfstein / Icon SMI / Newscom. The issue of juiced baseballs surfaces every couple years during the month of April due to a high rate of home runs hit. (original image)

Image by Associated Press. To try to discourage the mile-high bonanza at Coors Field, the Colorado Rockies started storing game balls in a humidor that kept the balls at a constant 70 degrees Fahrenheit and 50 percent relative humidity instead of Denver's typical 30 percent humidity. (original image)

Good Hitters—or a Juiced Baseball?

Every few years, during the month of April, Nathan says, batters start hitting home runs and the cry goes up: The baseball isn’t what it used to be! It must be juiced! (Why always in April? “Because in April there’s not enough data to be statistically significant…and people start to speculate,” Nathan says wryly.) The issue of juiced balls surfaced again in 2000 when the first two months of the season saw home runs hit at a notably higher rate than the same period the previous year.

To test the speculation that something had changed with the balls, the researchers compared the bounciness of balls from 2004 with a box of unused balls from 1976 to 1980. They shot the balls at a steel plate or a wooden bat at 60, 90, and 120 miles per hour and measured their bounciness after a collision—what physicists call the coefficient of restitution.

The result? “There was no evidence that there was any difference in the coefficient of restitution of the different balls,” says Nathan. One caveat: the scientists can’t say that balls made in other years aren’t livelier.

How times change, though: these days we’d more likely attribute a rash of home-run slugging to performance-enhancing drugs, not the ball.

The Humidor: Not Just for Cigars Anymore

Coors Field, home of the Colorado Rockies in mile-high Denver, is a pitcher’s nightmare and a batter’s nirvana. The air is only 80 percent as dense as air at sea level, and because there’s less air resistance, balls fly farther and pitches cannot curve as much. That means more hits and more home runs. For the first seven seasons at Coors Field, there were 3.2 home runs per game, compared with 1.93 home runs at the Rockies’ away games.

To try to discourage the mile-high bonanza, in 2002 the Rockies started storing game balls in a humidor that kept the balls at a constant 70 degrees Fahrenheit and 50 percent relative humidity instead of Denver’s typical 30 percent humidity. The idea was that higher humidity reduces the bounciness of the ball and slightly increases its weight. Indeed, the average number of home runs at Coors Field dropped 25 percent from 2002 through 2010.

But is the humidor really to thank (or blame) for the decrease in home runs?

To test the theory, the authors placed several dozen balls in conditions ranging from 11 percent to 97 percent relative humidity for weeks, and temperatures from the 30s to nearly 100 degrees, then fired them against metal cylinders that approximate bats. Again measuring the coefficient of restitution, they found that the colder and moister a ball was, the less bounce it had. Translation: a ball hit on a hot dry day at an Arizona ballpark will go noticeably farther than the same ball hit on a frigid, foggy day at Boston’s Fenway Park.

As for Denver’s Coors Field, the researchers calculate that a humidity increase from 30 percent to 50 percent would take 14 feet off a 380-foot fly ball—enough to decrease the chances of a home run by 25 percent.

Not long ago, Nathan says, a reporter in Arizona contacted him and told him that the Arizona Diamondbacks were considering installing a humidor at their stadium, too. Nathan did the math—this time starting at the desert-air base-line of 20 percent relative humidity, and conditioning balls to 50 percent relative humidity. “That would be an even greater reduction in the number of home runs, more like 37 percent,” he says.

The Diamondbacks later put those plans on hold. Everybody, it seems, likes at least a few homers between their peanuts and Cracker Jack.

Christopher Solomon is a writer in Seattle. In Little League, coaches usually stuck him in right field.

The Physics of Whisky’s Aesthetically Pleasing Residue

Smithsonian Magazine

Plenty of souls have searched for answers at the bottom of a glass of whisky. For Phoenix-based artist and photographer Ernie Button, that quest revealed some unexpected beauty, and set him out on a search for truth.

Over the last few years, Button has been capturing stunning images, like the ones seen above, of the dried patterns that whisky leaves at the bottom of a glass. Recently he teamed up with Howard Stone, an engineer at Princeton University, whose lab found that some basic fluid dynamics drive whisky’s unique pattern formation. They presented their findings today at a meeting of the American Physical Society (APS) in San Francisco, California.

Button’s fascination with whisky began when he married into his wife’s Scotch-drinking family. While doing the dishes at home, he noticed that lacy lines covered the bottom of a glass of single-malt scotch. Other glasses appeared to produce various patterns of dried sediment. “It’s a little like snowflakes, in that every time the Scotch dries, the glass yields different patterns and results,” says Button. He thought that trying to capture the patterns might make for an interesting photography project.

Creating the images required a bit of Macgyvering. On their own, the grayish sediment lines are a bit underwhelming compared to the amber liquid that creates them, so Button had to experiment with different glasses and lighting systems. Using flashlights and desk lamps, Button highlights the patterns with different hues. “It creates the illusion of landscape, terrestrial or extraterrestrial,” says Button. To him, many of the images appear celestial, perhaps something that a satellite camera might snap high above Earth. Other images could easily be frigid polar vistas or petri dishes of bacterial colonies.

Glen Moray 110 (Ernie Button)

Button captured a lot of variety through his camera lens, and he began wondering if it had something to do with the age of the liquid. After some experimenting, though, he saw little difference in younger and older versions of the same type of whisky. With some Googling, he came across Stone’s lab, then at Harvard and now at Princeton. Stone and his colleagues happily answered questions over email, and the conversation got them thinking as well.

Stone initially suspected that something called the coffee ring effect might be at play: When coffee dries, particles are pulled to the edge of where the liquid makes contact with the cup, creating ring-like patterns as the water evaporates. Similarly, the differing evaporation tendencies of alcohol and water can create interesting patterns, like the "legs" on a wine glass. This is largely driven by the Marangoni effect, first described by 19th-century physicist Carlo Marangoni. Alcohol and water have different surface tensions—that’s the degree of attraction liquid molecules have to other surfaces (in this case a cup or a glass). Alcohol has a lower surface tension than water, and alcohol evaporation drives the surface tension up and pushes more liquid away from areas of high alcohol concentration.

In the case of whisky, the patterns were more uniform, with particles settling in the middle of a droplet of liquid. So was there something about whisky that created unique patterns compared to other types of liquors?

Not a whisky drinker himself, Stone ran to the store to buy a bottle or two, and his team began tinkering around in the lab. Under the microscope, they made videos of whisky drying and compared them to videos of a mixture of alcohol and water that mimics the proportions of whisky (about 40 percent ethanol, 60 percent water). The fake whisky followed Marangoni flow: Ethanol evaporated first, drawing the particles into a ring-shaped pattern. The higher the alcohol content, the smaller the ring. But whisky, as Button had observed, didn’t produce clean rings. “That says there’s something in your mixture that’s missing,” explains Stone.

Next they added a soap-like compound, which sticks to the surface of water, to their faux-whiskey. Lots of compounds can do that, so they thought whisky might contain something similar. But the patterns still weren’t quite right. Next they added a larger molecule (a polymer) that might help whisky stick to the surface of the glass. Finally, the mixture droplets were doing roughly the same thing as whisky droplets.

Based on this work, the lab team has a hypothesis: “Very small amounts of the additives that come from how whisky is made contribute to the kinds of patterns you actually see,” says Stone. Different additives or variations in the manufacturing process might possibly produce different patterns.

The research has some practical implications. Better understanding of these types of fluid flows could prove useful in a lot of industrial situations that involve liquids, particularly liquids that contain particles of sediment or other material, such as printing inks. In the meantime, Button hopes his images raise questions in the minds of viewers that may give them some interesting conversation starters at cocktail parties. “The science behind the imagery provides that extra added layer of thought and complexity,” he says.

For more images and information about Ernie Button’s work and upcoming exhibitions, check out his website.

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