Banana Tatooing

At our August 23rd meeting we got updates from the teams on how their Water Balloon Challenge ‘devices’ are coming along. The Barcus Bunch showed their video on development and testing of the air-compressor powered water balloon launcher for the upcoming Water Balloon Challenge, raising the competition level for all of us making launchers!

Castlemaker kids take comis to tatoo some bananas.
Castlemaker kids take comics to tattoo some bananas.

Besides the air-powered units, there are reports of the classic latex tubing powered units and rumors of a Gatling gun style unit going for the quickest reload time category. It’s going to be an interesting competition, which will be at Big Walnut Sports Park on September 13th. Please check our events and project page for updates.

Some example tattoos that were made by using needles to bruise the skin.
Some example tattoos that were made by using needles to bruise the skin.

Our making project for this meeting was tattooing bananas. After first talked about how skin tattoos worked we then talked about the process of how fruit changes colors when bruised.

After putting bunches of bananas on the table, everyone took needles to bruise the skin so it turns brown. Some used Sunday comics to trace the character outlines on the banana, others just designed their own tattoo free-form. Conclusion: there’s nothing like personalizing your own banana so no one else will mistake it for yours!!

Liquid Nitrogen – August Meeting

What happens when you hit a marshmallow frozen at -196°C.
What happens when you hit a marshmallow frozen at -196C.

At our August 9th meeting we covered the Water Balloon Challenge, which is now up to 8 groups. Details on our project page, but they seem to be performing so well that we concluded that the Greencastle Farmer’s Market display in early September should be a demo, not the actual competition, since the Greencastle square may not be large enough!

What happens when you insert a balloon into liquid nitrogen. There's also a video where you see it shrink and then expand.
A balloon being shrunk by inserting into liquid nitrogen before re-expanding, the record was 4 times for one balloon!

For our ‘show & tell’ portion Chris brought liquid nitrogen in a dewar for experiments. After explaining describing liquid nitrogen and where it comes from, we poured the -196°C (-320°F) liquid over the marshmallows that Alice had brought in. We also froze a banana to drive nails into a piece of wood and then tried lots of things that kids and the adults suggested. Some that worked and some that didn’t!

A raw egg that was frozen first with liquid nitrogen then melted down during the meeting back into a normal uncooked egg.
A raw egg that was frozen first in the shell with liquid nitrogen then thawed down during the meeting back into a normal uncooked egg.

Freezing balloons was a big hit, the kids had tons of questions which you can hear and see in the balloon video that Brian H. took. For the coin collectors there, we showed how older copper pennies are more malleable at minus 200 degrees Celsius than the new copper plated zinc pennies – which shatter after hitting them with a hammer!

There’s another good regional event for science in Bloomington on 8/29, Makevention, along with some other events on our events page. Last year we took one of the shovercraft (shoveable hovercraft) to the Bloomington event and did demonstrations. It’s well worth the trip if even to just to look at what other people are doing.

Since we’re starting to look for projects after the Water Balloon Challenge, I can’t help but mention the Lexus created hoverboard that uses liquid nitrogen. I just watched a video (long version) on it, sort of outdid our shovercraft but a lot of more engineering in that design. Now that would be an awesome next project!