The Physics of the Macy’s Thanksgiving Day Parade Balloons

Should you double the radius of a balloon, you enhance the quantity by an element of eight (since quantity is proportional to the radius cubed). However what in regards to the materials on the skin of the balloon? Let’s say I wish to make every little thing honest and I enhance the thickness of the fabric by an element of two for the bigger balloon. Since this materials solely covers the floor space of the balloon, its space would enhance by an element of 4. Should you embody the double thickness, the fabric of the bigger balloon additionally has eight instances the mass of the smaller one.

However sooner or later, you don’t must hold making thicker and thicker balloon skins. I can get some materials (let’s say rubber) that could be very robust at only one millimeter thick. Which means if I enhance the radius of a balloon by an element of 10, the quantity will enhance by 1,000 however perhaps the mass of the shell solely will increase by 100. The amount is essential as a result of that’s the place I get my buoyancy pressure from.

Now let’s go the opposite means. Let’s make a balloon for ants. If I lower the radius of a daily get together balloon by an element of 100 (actually it ought to even be smaller than that), the thickness of the shell must additionally lower by 100. These balloons are already fairly skinny. Lower an excessive amount of and also you simply wouldn’t have a construction able to holding the balloon collectively. Enhance the thickness a bit bit and the mass will get too excessive to drift. Sorry, no parade balloons for ants.

Larger Balloons Are Extra Tough

Yay! I’ve a large balloon and it floats. What might be extra superior? Oh certain, I’m going to wish a bunch of individuals to carry it down (together with a few autos), but it surely’s nonetheless a large balloon. However wait. Large balloons nonetheless have issues. Making issues larger would possibly make it simpler to drift but it surely provides different points.

The primary drawback is wind. Positive, that breeze in your little hand-held balloon is annoying. However what occurs once you enhance the balloon dimension? This pressure pushing on the balloon is proportional to the cross-sectional space. Should you double the radius of your balloon, you enhance this space by an element of 4, which supplies 4 instances the air pressure.