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Balloon Fiesta by Andrew and Alex

We live in one of the coolest cities, or should we say hottest? We live in Albuquerque, New Mexico, home of one of the biggest hot air balloon festivals anywhere. We hope to get up in one of those giant balloons someday, but in the meantime, we're doing some investigating on a smaller scale. We visited our favorite science hangout, Explora, to find out: How big does a hot air balloon need to be to lift things off the ground?

What did we do?
Using the heat from a hot air gun, we tried flying different sized plastic bags. We discovered that a bag had to be large to actually take flight. Then we decided to make our own balloons out of tissue paper. We calculated the volume of our balloons by multiplying length x width x height. We used an infrared thermometer to take the temperature inside our balloons. Since real hot air balloons carry weight, we also experimented with 3 different size tissue balloons to figure out how much each balloon could carry. We figured out the mass of each balloon by weighing the balloon and the gondola we fashioned out of a small pie tin. We experimented with how many pennies each balloon could lift off the ground. We collected data and graphed our results.

What did we find out?
We used the data from our investigation to make an estimate of how large we thought an actual balloon at the Balloon Festival would need to be to lift a 2,000 pound load. Turns out we were about 30,000 cubic feet off. So we're back to the old drawing board. But first, we took a ride in a balloon at the festival. Awesome!

What can you do?
• Think about different ways to make a model hot air balloon. What materials should you make it from, and what shape? Hot air can safely be provided by a hair dryer. Design a strategy for building a balloon, measuring or estimating its volume, and measuring how much it can lift. Write your ideas in your notebook.

• Helium balloons are a fun way to explore the concept of "neutral buoyancy". Acquire some helium filled balloons (either ordinary latex balloons, or those shiny decorative Mylar balloons). Try hanging various weights on to the balloon, so that it just hovers in the air without rising to the ceiling, or sinking to the floor. Try to estimate the balloon's volume, and the mass of the balloon and weights, then use these findings to estimate just how big a balloon it would take to allow you to hover!

• Swimming noodles make great science experiments. These fun toys seem capable of floating even the heaviest swimmers! Design an exploration in which you determine exactly how much one of these noodles can support. You might need to measure things like the mass of the noodle (in air), the noodle's dimensions to find its volume, etc. Take into account that when you are in the pool floating with a noodle, the water itself is helping to float you... the noodle isn't doing all the work by itself!

 Go to the DFTV Boards, and tell us about your science investigation.