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Hotchalk Global

news & tips

A collection of helpful articles on teachers and teaching

Balloons and a Boy

Unless you have been on another planet you know about the Balloon Boy hoax. This is where the little 6 year old guy in Colorado was believed to be in a helium balloon shaped like a flying saucer. However, it turns out it may have been a planned stunt for publicity. Well, there is a ton of science in that unusual bit of news. First, the scientists who are good at geometry determined that a small boy would not fit in the small compartment at the bottom of the balloon.

This was either done by jamming a willing 6 year old in there or by measuring the volume of the small compartment and estimating the volume of the 6th grade boy who was believed to have been lost. Some science is estimating. The real science came in the balloon lift load. The balloon was filled with helium which is less dense than air and will rise in air. The balloon was mylar and I am sure some folks will give you the mass of the mylar skin and the box beneath. We do know that helium will lift one gram per liter. It takes about 4,000 balloons to lift a light weight man or woman. If the 6 year old boy weighs about 50 pounds which is 22 679.618 5 grams,  it would take at least 22, 6180 liters to lift Falcon Heene into the sky.

According to CNN the craft was roughly a cylinder 20 feet in diameter and 5 feet high. The volume of a cylinder is the area of the base times the height. (Area of the base = pi x radius^2 = 3.142 x 10? x 10 = 314.2 square feet.) The volume of the craft, 314.2 square feet, times 5 feet is 1,571 cubic feet. Converted to liters that is 44 485.78 liter. Even if the balloon weighed 50 pounds and it probably did not, it could have lifted the 50 pound boy.

But, knowing what we do about lift, drag and gasses we know that if you have a big balloon with a heavy mass at the bottom it tends to deform a bit into a teardrop shape. One of my students noticed that right away and said the shape is not right for the balloon to have a 50 pound mass at the bottom. It turns out she was correct. This would be an exceptional opportunity for some observation and some math integration. Give the students the numbers to calculate the volume of the balloon and convert the mass to grams and the volume to liters.  The conversions are then real life and have meaning. I always have to show my kids that the metric system comes in handy. Here is a chance to use an interesting investigation and news story to see if science could have told us the truth from the start and saved a lot of folks some search time. There are videos all over the web and having the students observe the videos is a good exercise in inquiry skill development. The bottom line is that it is good to use what everyone is talking about to get to some science meat. This story is fascinating to the kids and the science, well it is just plain handy.

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