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Earthquake Machine/Lava Lamp |
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Written by twinlamps
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Saturday, 06 January 2007 |
Earthquake Machine/Lava Lamp
Episode: # 60
Original air date: August 30, 2006
Earthquake Machine
The myth: Did Serb-American inventor, physicist and engineer Nikola Tesla invent a working earthquake machine?
The Experts:
None
Memorable/Quotable Moments:
Adam: We're 100 feet away, and I can still feel it moving the bridge...it's eerie.
Rob Lee: But, when Adam said, “We promise that if this works, we'll use this power only for good.”, he was lying.
Action/Results:
In this episode, Adam and Jamie focused on Tesla’s own recounting of a working earthquake machine that he built himself. After researching the myth, they found one of Tesla’s designs-the Tesla Oscillator. The design was a motorized mechanical oscillator generator with a central rod and an air cushion.
(See “Breakstep Bridge” for more on the destructive potential of mechanical resonance, as this concept is similar to this myth.)
For the first prototype, Adam and Jamie used a jackhammer. They replaced the chisel with a rod and added an aircushion. Adam and Jamie argued over the machine as the air spring caused the machine to oscillate very slowly. Jamie in particular was not happy with the inefficiencies the air cushion apparently caused.
For the second prototype, the boys compromised. Jamie replaced the air cushion with mechanical springs. This test was done on a two-foot steel bar, in keeping with Tesla’s recordings. The springs broke.
Back to the drawing board! They set up a water tank with a ping pong ball bouncing vertically inside. Variations in the ball’s frequency, even small ones, caused big wave variations on the water surface. This further visualized the mechanical resonance, and they went onto another prototype.
For the third prototype, they used an air-powered auto tool. The design was very close to Tesla’s original. All they did was put a plate on the tool, to attach it to its target object. Adam and Jamie returned to the steel bar test, but couldn’t tune the device and the bar simultaneously. Despite trying with square tubing and a 20’ bar, there were no destructive vibrations.
Grant to the rescue! Bringing an electromagnetic linear motor, they attached it to the 20’ bar, causing it to bounce steadily. With this success, a 1/6 test was created with a scale model of a building and a scale model of Tesla’s Oscillator. Nothing happened when they attached Grant’s device to the scale building. This myth was looking busted, but Adam wanted to test it on a bridge!
Bridge test.
Going to the Carquinez Bridge, they attached Grant’s device to a support. The bridge started to oscillate, but after an hour, no earthquake. Myth BUSTED.
Exploding Lava Lamp
The myth: If heated on a stove, can a lava lamp cause a lethal injury when it explodes?
The Experts:
Memorable/Quotable Moments:
Grant: "The theory was that the shock of the cold water would cause the glass to fracture -- BOOM!" (third test, as the lamp explodes)
Tory: "I can taste beans in the air" (testing the can o’ beans)
Action/Results
If it’s one thing the Mythbusters are good at, it’s making ordinary objects explode with maximum force. So, the Build Team explored a myth where a person was killed by shrapnel from an exploding lava lamp.
First Kari used a ribcage and ballistics gel for a “human” chest. She also suspended a balloon heart inside, so everyone would know when/if it pierced.
First test: Safety-cap Lava Lamp
Attaching the lava lamp to a stove, with heating the safety cap blew off in a geyser of lava lamp contents. HOT lava lamp contents. The lamp itself shattered over the stove.
Second Test: Bottle-cap Style Lava Lamp
Due to a pressure build-up there was a small leak at the cap, which in turn caused the lamp to go on fire. The lamp exploded into the ballistics gel chest. The result? A nasty injury, but not a lethal one.
Third Test: Secured Lava Lamp
With this lamp, no pressure was supposed escape (thanks to Tory’s epoxy). Some pressure DID escape through the lamp’s sides, causing another leak. The team decided to squirt water on the lamp, with the result being a nice explosion, and a shard of glass stuck deeply in the ballistics gel torso.
CONFIRMED!
For fun they tried this using other household objects. All were placed on a stove.
Can of beans - RESULT: Non-lethal
Big can of beans - RESULT: Possibly lethal
Spam – RESULT: Non-lethal, but, as Grant said, “very messy”
Glass jar of milk – RESULT: Possibly lethal if someone was looking down at it.
Big Bertha Lava Lamp – RESULT: The lamp shattered into possibly lethal shrapnel.
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