Dropping The Nitrogen Bomb In Science Class

We took Geology in college. It was pretty cool learning about the hardness of different minerals. But there were no explosions involved. We’re not entirely sure what this class is, perhaps Chemistry, maybe Physics, but we want in. [Dr. Roy Lowry] wows the class with a bomb made of liquid nitrogen. The demonstration was part of his lecture at Plymouth University.

A small explosion is cool, but [Roy] knows how to add the wow factor. To make the bomb he filled a one liter plastic bottle about 1/3 of the way with liquid nitrogen. After tightly sealing the cap it was dropped in that garbage can which had a pool of warm water in it. Before quickly running away he and his assistant dumped a few garbage bags of ping-pong balls on top of it all. When the plastic bottle bursts under the pressure of the expanding gas it sends the garbage can about six feet into the air and floods the room with bouncing white balls. See the whole presentation for yourself in the clip after the break and don’t forget the sound so you can catch the oohs and aahs at the end.

Looks like a Hackerspace recruitment tool if we’ve ever seen one.

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Adding Payload To An RC Cessna

For just a few bucks you can add a payload to your flying toys. In this case it’s a Cessna RC plane which now has an added surprise. The first thing to be dropped was a parachute with a weight on it (for testing purposes). But there are hints of future projects that will use the same system for different purposes.

As you can see in the image above, the system depends on an additional compartment attached to the bottom of the plane. It was built from foam board to keep the weight down and connects using rare earth magnets. The bottom of the enclosure acts as the door, hinging on a servo motor with a bamboo skewer as the axle. So far the test drops have gone pretty well, but some more work needs to be done with the parachute design. It only opens about 60% of the time. We can sympathize, having had to work out some of our own parachute issues.

Don’t miss video from the plane as well as the ground after the break.

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Defusable Alarm Clock – Wastes Wire But Fun For The Kids

Nothing makes you feel the pressure of getting out of bed in the morning like a ticking-time-bomb on the bedside table. It may look like it came in the mail from ACME, but all that went into this is some wooden dowels covered in craft paper and an Arduino-compatible board. The 7-segment display can act as a clock, or count down to your doom. You can set an alarm that requires you to clip the wires to shut it off. Each time that alarm is set the wires are randomly chosen; one will set of the bomb, one will safely defuse it, and the others do nothing. See for yourself after the break.

The wires are easily replaced because they are connected via terminal blocks. It still seems like an awful waste of wire. We like the Think Geek bomb clock concept that works in much the same way but uses wires that have a male/female RCA plug pair that can be disconnected and reconnected without waste.

This one will apparently be available as a kit, at which point the schematics and code will be released. But it shouldn’t be too hard to build one from scratch yourself, and it’s an obvious winner if you’ve got kids.

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Booby Box – It’s A Trap!

Here’s a puzzle oddity that challenges you to open the box without falling into one of the booby-traps. It was built as a side-distraction from the more serious events happening at Insomni’hack 2011. [Sergio] and a colleague built the box to resemble a ticking bomb like in the blockbuster action movies we know you look forward to seeing each summer. A display on top of the device counts down for ninety seconds with an audible beep to mark the passage of time and boost your tension level. See it ticking away in the clip after the break.

Two wires meet at the edges of the box halves, completing a circuit that will set off an alarm when the contact is broken. There’s also a photocell on the bottom of the box which triggers the alarm if you lift it and expose this sensor to light. The combination necessary to open the box was provided to each competitor; it was not a numerical code, but a color code. Three potentiometers control the red, green, and blue anodes of an RGB LED, while being monitored by an Arduino at the same time. If you can dial in the appropriate color, the lid trap is disabled and the box can be opened. What does the winner get? Why an Arduino, of course!

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Thanksgiving Turkey Quadcopter Shenanigans

The challenge: can you build a flying turkey that drops pumpkin pie bombs? That’s the question that Utah Aerials asked themselves and they did manage to make it happen. Of course they’re not starting from scratch, but adding a little holiday cheer to an existing quadcopter in the form of a spray painted turkey fuselage. The cheapest pumpkin pie they could find was hung from the copter with care, and dumped thanks to a servo motor. Check the video after the break to see if they were able to hit their balding-bullseye or not.

Seems like the wicked witch music should have been the background for that video.

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