9 Animated GIFs That Show How Machines Really Work

GIF animated images are useful when it comes to learning how stuff works. 

They can make topics as tortuous as trigonometry interesting and fun, but they can also be used to show how normal, real-world stuff works. 

From Reddit's impeccable EducationalGifs subreddit, here are nine GIFs that show you how cool stuff really works:

First of all, here's how a key opens a lock: 

Tomorrow Started

And here's how you pick a lock. The tool on the bottom is a torsion wrench, exerting rotational pressure like the key would. The pick does what the key would do to each of the pins one at a time. 

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How an AK-47 works:

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How the Geneva drive — the mechanical step that makes the second hand on a clock work by turning constant rotation into intermittent motion — functions.

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How an electric motor works:

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How a four-stage gasoline engine works. Blue is a gas-air mixture, red is an exploding gas-air mixture, and black is exhaust:

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Here's how an aircraft's radial engine works:

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How a sewing machine functions:

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How a zipper works:

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