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# The Little Cube That Could

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So here's something neat that I just stumbled across on YouTube. It also connects to our current unit of rotational dynamics perfectly. Its called "Cubli" which a compound of the English word 'cube' and the German word 'li' meaning something small in size. Cubli is basically a 15x15cm cube that can move and balance with the help of angular momentum. It contains three flywheels are able to achieve high angular velocity (ω) and acceleration and react quickly to external forces with the help of sensors that detect changes in inertia and then change the angular velocity of the wheels. The system is accurate enough to balance cubli on its edges and corners, and remain balanced even after being pushed. Whats more, by spinning the flywheels very fast to create angular momentum and then stopping suddenly cubli can create enough force pop itself up from laying flat to balancing on a corner. This is because of the impulse-momentum theorem which states that impulse=momentum so angular momentum=L=Iω=imulse=FΔt, so Iω=FΔt, and solving for force F=Iω/Δt. Since I (moment of inertia) is a constant, cubli is able to spin its flywheels fast enough and stop them is such little time that it is able to create enough force throw its mass onto an edge and then corner, and then react fast enough to balance. Here's a video of the cubli in action.

## 1 Comment

Gotta get me one of those!

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