![]() Gears-we'll call them "power gears" (to avoid confusing them with the The only trouble is, the weight is going toįall really quickly and the second hand will whizz around too fast so Will pull the axle around, turn the second hand, and that will drive You could wrap a piece of stringĪround the axle and attach a weight to it. To do is count seconds, turn the second hand, and the rest of the jobīut, hang on, that's still pretty tedious. Likewise, turns the hour hand at 1/60 of its speed. Turns the minute hand at 1/60 of its speed, and the minute hand, We'll call "timekeeping gears," so that the second hand automatically Things? You could mount the hands on a little axle driven by what Some clock! That's going to get tedious quite quickly, so what about automating Seconds, and the hour hand once every 60 minutes (3600 seconds). Move the second hand once a second, the minute hand once every 60 You could start with a dialĪnd some hands and move them around the face with your finger,Ĭounting seconds to yourself and moving the hands accordingly. Possible with the fewest number of parts. Suppose you want to build a clock from scratch in the simplest way Galileo Galilei How does a pendulum clock work? and on this new principle, that the pendulum makes its great and small vibrations in the same time exactly, they will invent contrivances more subtle than any I can suggest.” “ I do not make use of a weight hanging by a thread, but a heavy and solid pendulum, made for instance of brass or copper. ![]() (Read more about Huygens and his clocks and see a photo of the first Huygens pendulum clock of 1656.) ![]() Was designing just before his death) it was left toĪnother brilliant scientist, Dutchman Christiaan Huygens (1629–1695), He came quite close (here's a model of the Which just means "equal amounts of time") is what makes a pendulum so usefulĪnd though he never actually managed to build a complete pendulum clock. It doesn't climb asįar, but it covers the shorter distance more slowly-so itĪctually takes exactly the same time to swing. But even as it slows down, it keeps time. Steal a bit more energy from the pendulum and it gradually comes to a ![]() In reality, each swing sees friction and drag If there were no friction or drag (air resistance), a pendulum would Harmonic motion, though we won't go into those things here.Īrtwork: A pendulum is constantly swapping potential energy and kinetic energy. Oscillator and its movement is an example of simple Something that works this way is called a harmonic Repeatedly switches its energy back and forth between potential and So as the bob swings (oscillates) back and forth, it Movement) and then, as the bob climbs up again, back to potentialĮnergy. Potential energy is converted into kinetic energy (energy of As it acceleratesĭown toward its lowest point (its midpoint, nearest the ground), this Ground), it has maximum stored energy ( potential energy). When the bob is highest (furthest from the That you need to quadruple the length of a pendulum to double the time it takes to make a swing.Ī pendulum works by converting energy back and forth, a bit like a Here, l is the length of the pendulum and g is a measure of gravity's strength (what we call the acceleration due to gravity). Pendulum swings is its length and the strength of gravity.įor relatively small swings, the time (T) it takes to make one complete In theory, the only thing that affects how fast a Pendulum is that it always takes the same amount of time to make one Galileo Galilei (1564–1642) discovered, the clever thing about a Side to side due to the force of gravity. Weight called a bob hanging from a string) that swings from A pendulum is a rod hanging vertically from its top end (or a
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