# How does the LEGO Levitating Contraption work? ProPreview

LEGO Levitating contraption appears to just... FLOAT IN THE AIR!?!? We can confirm, it really works! But how?

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• #1607
• 17 Apr 2020

As you can expect, it is all physics! You will be amazed at how simple it really is. All we need to do is write down all the forces that apply to this structure.

The first force, that keeps this thing together is gravity! As you might have heard, gravity pulls objects from their center of mass. Where is that in the upper structure? Somewhere below the center of the rectangle and also it is a bit forward.

So, to keep the upper part from falling, we tie it to the support structure with a string! Now the string pulls the upper part upwards, because of Newton's third law.

For every action, there is an equal and opposite reaction.

Notice how the two forces have a bit of distance between themselves. Do you know what will happen to the structure if we let it fall as is? The two forces will create a spinning motion and it will fall. The spinning motion makes the back end go upwards and that is very useful because we can just tie it to not do that!

And it is that easy! You just find what force makes the parts fall and stop it. There is one more thing that we should mention. Can you think of why we tie the upper part with two strings and not only one? That is because with only one string the upper part will spin sideways and fall. That is why we tie it with two strings so that it doesn't twist sideways.

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