A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force combined with the pendulum’s mass causes it to oscillate about the equilibrium position, swinging back and forth.
The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum, and also to a slight degree on the amplitude, the width of the pendulum’s swing.
From its discovery in around 1602 by Galileo Galilei, the regular motion of pendulums was used for timekeeping, and was the world’s most accurate timekeeping technology until the 1930s. Pendulums are used to regulate pendulum clocks, and are used in scientific instruments such as accelerometers and seismometers. Historically they were used as gravimeters to measure the acceleration of gravity in geophysical surveys, and even as a standard of length. The word ‘pendulum’ is new Latin, from the Latin pendulus, meaning ‘hanging’.
The simple gravity pendulum is an idealized mathematical model of a pendulum. This is a weight (or bob) on the end of a massless cord suspended from a pivot, without friction. When given an initial push, it will swing back and forth at a constant amplitude. Real pendulums are subject to friction and air drag, so the amplitude of their swings declines.
The period of one complete cycle of the dance is 60 seconds. The length of the longest pendulum has been adjusted so that it executes 51 oscillations in this 60 second period. The length of each successive shorter pendulum is carefully adjusted so that it executes one additional oscillation in this period. Thus, the 15th pendulum (shortest) undergoes 65 oscillations.
Our apparatus was built from a design published by Richard Berg [Am J Phys 59(2), 186-187 (1991)] at the University of Maryland. The particular apparatus shown here was built by our own Nils Sorensen.
“America is not the greatest country in the world anymore”
2012 TV series
~~Published on Oct 21, 2012~~
“…It’s NOT the greatest country in the world, Professor. That’s my answer.
Fine. Sharon, the NEA is a loser. Yeah, it accounts for a penny out of our paycheck, but he gets to hit you with it anytime he wants. It doesn’t cost money. It costs votes. It costs airtime. And column inches. You know why people don’t like liberals? Because they lose. If liberals are so fuckin’ smart then how come they lose so goddamn always?
And with a straight face, you’re gonna sit there and tell students that America is so star-spangled awesome that we’re the only ones in the world who have freedom? Canada has freedom. Japan has freedom. The U.K. France. Italy. Germany. Spain. Australia. BELGIUM has freedom. Two hundred and seven sovereign states in the world, like, a hundred and eighty of them have freedom.
And you, Sorority Girl, just in case you accidentally wander into a voting booth one day, there’s some things you should know. One of them is there’s absolutely no evidence to support the statement that we’re the greatest country in the world. We’re seventh in literacy. Twenty-seventh in math. Twenty-second in science. Forty-ninth in life expectancy. A hundred and seventy-eighth in infant mortality. Third in median household income. Number four in labor force and number four in exports. We lead the world in only three categories: Number of incarcerated citizens per capita, number of adults who believe angels are real, and defense spending, where we spend more than the next twenty-six countries combined, twenty-five of whom are allies.
Now none of this is the fault of a twenty-year-old college student, but you nonetheless are without a doubt a member of the worst, period, generation, period, ever, period. So when you ask what makes us the greatest country in the world, I dunno what the fuck you’re talkin’ about.
Sure used to be. We stood up for what was right. We fought for moral reasons. We passed laws, struck down laws, for moral reasons. We waged wars on poverty, not poor people. We sacrificed. We cared about our neighbors. We put our money where our mouths were. And we never beat our chest.
We built great big things, made ungodly technological advances, explored the universe, cured diseases, and we cultivated the world’s greatest artists and the world’s greatest economy. We reached for the stars. Acted like men.
We aspired to intelligence. We didn’t belittle it, it didn’t make us feel inferior.
We didn’t identify ourselves by who we voted for in the last election, and we didn’t, oh, we didn’t scare so easy. Ha. We were able to be all these things and do all these things because we were informed. By great men. Men who were revered. First step in solving any problem is recognizing there is one. America is not the greatest country in the world anymore. Enough?”