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# Spontaneous balloon popping - Page 3

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Now, let's take another look at the simulation. As you may have guessed, the internal structure of an actual balloon's rubber membrane doesn't look exactly like it's represented here, but several layers of circular barriers containing holes does approximate the membrane's structure pretty well. In this simplified version, each layer contains the same number of holes and each hole is the same size, regardless of which layer it's in. In the Control Panel, you can now adjust the number of layers (which is like balloon thickness), the number of holes per layer, and the size of the holes. You will use these controls for some of the exercises that follow. The space inside and outside the balloon will start off empty but you can add SF6 inside the balloon by clicking on the button labeled "Add SF6" and you can add N2 outside the balloon by clicking on the button labeled "Add N2"

Note: To simplify this problem a bit, in all of these exercises, assume that the number of layers making up the balloon's rubber membrane does NOT influence how easily it pops. That is, the pressure at which it will pop is independent of the number of layers making up the membrane.

1. Imagine you're a prankster and you want to foil the professor's demo by replacing the balloons he normally uses with custom-made balloons that won't pop. You have to design and make these balloons yourself since they're not available at the store. How would you do this? Use the simulation to find a number of layers, number of holes, and hole size that might work. Why wouldn't your balloon pop?
2. Now imagine you're friends with the professor and you discover the plot to substitute balloons that will undermine his demo. You decide to intercept the non-popping balloons and substitute your own balloons that will really work well and pop quickly. How would you design such a balloon? How many layers, holes per layer, and what hole size would you use? Use the simulation to check to see if your intuition is correct.
3. Imagine that, instead of using the balloons in a class demo, you want to use them to freak out your roommate while she's sleeping. This means you want the balloons to be filled for a long time before popping. How would you design that type of balloon?

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