MacGyver Season 3 episode 12 Science notes: Fence + Suitcase + Americium-241

Toothpick in grenade

It’s not a super Mac-hack, but it works. The only thing MacGyver does is to put a toothpick in place a grenade pin. It only works for a little bit before the grenade explodes. However, the physics discussion is pretty good. Let’s go over some of the terms.

  • Tensile strength. This is essentially the maximum force a material can withstand when being pulled apart. Just imagine a rope—how hard can you pull on the rope before it breaks. That would be the ultimate tensile strength. Yes, wood has a pretty high tensile strength.
  • Compressive strength. How hard can you squeeze the thing before it fails? Something like concrete has a very high compressive strength, but not so much with tensile strength. Wood could have a good compressive strength if it’s wide and short. Long skinny boards of wood tend to buckle.
  • Sheer strength. This is the maximum force an object can withstand when two forces are pushing in opposite directions but not directly at each other. Think of scissors.

What is a dirty bomb?

This is another non-hack. However, I just want to describe the difference between a nuclear bomb and a dirty bomb. A nuclear bomb uses a nuclear reaction (usually started with conventional explosives) to make a massive boom.

The dirty bomb is NOT a nuclear explosion. Instead, it uses conventional explosives to spread radioactive material around. It’s dirty.

Electromagnet

MacGyver builds a strong electromagnet to move a bolt inside a locked door. Yes, this is possible. You would need a strong electromagnet—that means high electric current and thus thick wires. You also need a fairly beefy battery to get this much current.

Oh, one possible problem. If the bolt is ferromagnetic (steel) and so is the door, then it’s going to be difficult to get that bolt to move. However, if the door is aluminum or some type of non-ferromagnetic material then this would work.

Wall walk

There are two methods to get over the pressure sensitive floor (they end up not using this though). There is a wall-walking stilt method and a rolling sled method. Both have the contact point with the wall at an angle—this is needed in order to work (because of physics).

Let me just start with a setup that would only barely work. Here is a view of a person using completely horizontal stilts along with the forces on the person.

The first problem is that the stick the reaches across the hall would have to fit perfectly. The harder it is pushed against the wall, the greater the frictional force. And it is this upward frictional force that balances the weight pulling down.

The second problem is with these horizontal arms. When they attach to the person, there is no upward force. This would be like trying to hold a rope with a weight in the middle perfectly horizontal. It won’t work.

Here is a better option.

This setup fixes both of the problems. The sticks can be longer than the hallway (and not fit perfectly) and there is now an upward component from the wall that helps support the human.

Mercury Switch

What is a mercury switch and how can you build something similar? Here, I made a video for you.

Smartphone Radiation Detector

MacGyver uses some smartphones (as usual) to detect radiation from the dirty bomb. This is essentially real.

A smartphone camera has a sensor that is normally used to detect light. However, this same sensor can be set off by other types of radiation—like the stuff that is produced by radioactive stuff.

In order to actually detect this radiation, you need to block the light from getting to the camera—electric tape over the lens will do the trick.

But wait! There is a real project that uses normal human smartphones to detect cosmic radiation. Check it out—the CRAYIS Project. https://crayfis.io/

Rolling Tire Bomb

Yeah, mixing stuff and make explosions. The end.

MacGyver Season 1 Episode 8 Science Notes: Corkscrew

Remember, I’m just going over the MacGyver hacks with science stuff in them.

DIY Blacklight

This one is fairly legit. MacGyver is in an escape room and needs to find a blacklight to read some hidden words on the wall. He says it would be easier to build a blacklight than it would be to find it.

Here is MacGyver’s build. Use a smart phone LED light and an old floppy disk. In theory, this could work. Here is the short answer: most white LED lights work by having an ultraviolet light with a fluorescence coating to produce white light (which is the way the old school tube-like fluorescent lights work). This means that the white LED also produces UV light (also called blacklight). You just need to block out the visible light—and that’s where the floppy disk comes in. If you take the actual disk out of the floppy, some of them block visible light.

I actually wrote a WIRED post on this—here it is.

https://www.wired.com/2016/12/make-uv-light-phones-led-flash/

Fluorescence of stuff on the wall 

The second part of this hack is to use the DIY UV light to read the stuff on the wall. Here’s how that works.

Electrified stair rail

A bad guy is getting away and running down a stairwell. MacGyver pulls some wires out of a wall light and touches one of the wires to the rail and the guy gets shocked and falls.

Would this work? Maybe. In order for the guy to get shocked, there has to be a complete electrical circuit that passes through the dude. That means the current would come out of the wall, go to the rail, go to the guy, go OUT of the guy, and then back to the wall.

In order to get through the guy, he would have to be grounded and the rail would have to NOT be grounded. I suspect that building code requires a rail to be grounded for safety—but you never know. In order to get the guy grounded, he would have to stand on conducting ground (like metal) and have terrible shoes.

But still, it’s at least possible.

Hacking magnetic lock

MacGyver is trapped in another room—with essentially nothing in it. He grabs some wire out of the ceiling panels can fishes out the wires for the security pad. Then he manually enters the keypad code by connecting wires.

OK, this could work. However, it if it’s a legit security pad it would probably be harder to hack.

Wine bottle rocket

MacGyver takes some wine bottles, dumps out some of the wine and recorks them. Then he pumps them up and let’s the cork pop out. Now it’s a water bottle rocket.

Here is the launch in slow motion.

Of course like many MacGyver hacks, this is real. The only problem is that it would take a normal person a few minutes to set up and not a few seconds.

Radio jammer

MacGyver needs to take out some remote controlled guns. He grabs a CB radio from a truck and hooks it up to a large power supply. This broadcasts enough static to jam the radio signal to the guns.

Let’s go over the details.

  • Could he get a CB out of a truck? Yes. Easy (but it wouldn’t be as quick as he does it).
  • Could he hook it up to a power supply? I think he used the power lines to some metal crusher. This probably wouldn’t work. The CB runs on DC current and the big power is probably AC. Also, it probably expects 12 volts.
  • Would this jam the signal? Here’s where he might get lucky. If the guns run on the same channel as the CB —it would work. If the power supply messes up the radio so that it just somehow broadcasts on a bunch of frequencies—it would work.

So, it’s possible.

MacGyver Season 1 Episode 7 Science Notes: Can Opener

Let’s do it.

Ring of fire

MacGyver uses a fire hose to spray gasoline on the ground and then Jack ignites it with a bullet. It looks cool, but there are two problems. One small problem—bullets don’t make sparks (usually)—http://www.cracked.com/article_19781_6-stupid-gun-myths-everyone-believes-thanks-to-movies.html.

Oh, also gasoline doesn’t always burn that well.

OK, but gasoline CAN burn and bullets CAN make sparks—so this isn’t completely crazy.

Fixing an inhaler

MacGyver uses part of a plastic force to fix the part that pushes the release valve of a broken inhaler. This is exactly the kind of thing MacGyver would do.

Battery hydrogen bomb

OK, this is mostly real—but very awesome. Here’s how it works. If you put an electric current through some water, you can break the water into hydrogen and oxygen. In order to do this, you need the water to be able to conduct electricity. NEWS FLASH: pure water doesn’t do this. If you add some salt, water conducts just fine.

Now with the current going through the water, you get tiny bubbles. Bubbles on one electrode (I can’t remember which) are bubbles of hydrogen gas. The other set of bubbles on the other electrode are oxygen.

You can seriously do this on your own. It’s really not hard.

But how would you make an explosion? You can let the hydrogen and oxygen gas mix together—nothing will really happen until you get a spark to star the reaction between the two gases at which point BOOM.

So, in the case of MacGyver he wants to let the hydrogen gas collect at the ceiling. Yes, the hydrogen gas would rise but it’s also difficult to contain. Any tiny crack and it’s gone—but still, it’s a good idea.

What about the ignition? A spark will do. Yes, you can indeed get a spark from a fluorescent light. Especially from the ballast since it makes a high voltage.

Oh, one more comment. What about the 2 psi pressure difference? Is that possible? Probably. Would it knock the door off? I think so—especially if the pressure change is quick. Would it be bad for humans? Could be.

Morse code with the tail lights?

Totally legit.

Final breakout part 1: making liquid nitrogen

OK, this is a stretch. MacGyver uses a carbon dioxide fire extinguisher and some alcohol to make liquid nitrogen. It doesn’t say liquid nitrogen, but that’s what it is (from the air). Let me just show this video:

See. It’s possible. It’s not easy, it’s possible. What about the dry ice? Well, that’s another stretch. Expanding carbon dioxide from a compressed tank CAN INDEED make dry ice. In fact, that’s how we do it in chemistry sometimes.

Final breakout part 2: breaking steel

MacGyver takes the liquid nitrogen and puts it on some steel bars. The get super cold and breakable. The first problem: you would need a lot of liquid nitrogen to cool off the metal. But OK. The second problem—there really isn’t another problem. If you get it cold enough, I think it would work.

Adventures in Spark Gaps

I wanted to build a spark gap transmitter—you know, for fun.  However, things didn’t start off so great.  Here is how it went down.

My first plan was to build this.

I like it, but it uses an ignition coil and some other thing.  However, check out the receiver.  That’s awesome.  It’s a coherer receiver (I think) and it basically detects a spark with those two bolts in the plastic sleeve.  There should be some iron filings or something in between the bolts.  When a spark is detected, the filings jump the gap and make it a conductor.  I’m not sure why the LED light is connected to a 9 volt battery though.

After that, I just did some google searches for spark gap transmitter and attempted to build the designs I saw.  None of them had capacitor values, so I just had to guess.  But they didn’t work.

I honestly thought I knew how to do this.  I tried a step up transformer with a capacitor.  Nope.  Actually, I was getting a spark on the battery side but not the step up voltage side.  How did I even pass physics courses?

Here is my attempt with a transformer.

Finally, I found a page that used an electromechanical bell.  That works.

I decided to build my own oscillator from scratch.

Homework (for me)

  • Make this more solid (the connection to the steel plate is iffy.
  • Could you replace the steel plate with a paperclip?
  • Can you change the buzzing frequency by adding weights to the oscillating bar?
  • Use a step up transformer to get BIGGER SPARKS.
  • What about an antenna?
  • Build a coherer detector.

Fixing Stuff Isn’t So Bad

Today it started with a lose bolt that holds down the toilet.  Actually, the bolt was gone – beyond gone.  Rusted away.  I figured the flange thing that the bolts go into was probably busted too, but you can’t tell until you lift up the whole toilet.

When starting a project like this, I always go to youtube first.  What a lucky time to live in that we have a resource like this.  Of course it wasn’t just the broken bolt.  I needed to replace the wax seal too.  As long as I’m working on the toilet, I should also replace that tank fill valve that was slightly leaking.

Oh wait! When I turn off the water to the toilet with the shutoff valve, that is leaking too!  After a trip to the hardware store and multiple rounds of turning off the water to the whole house, I finished the job.  The seat doesn’t rock, the shutoff valve doesn’t leak, and the fill valve stops when fill.  Oh, how about a quick advertisement for those quarter-turn shutoff valves?  My house has these “multi-turn” valves that are like the kind on your outdoor water hose.  I’ve already had two of these leak – so that’s not so good.  Also, when the toilet overflows (it happens), the quarter turn is faster to shut off.

 

IMG_5448

Photo: Rhett Allain

I’m just going to say one other thing about toilets (this is not a toilet post).  It seems like a pretty simple job – but once you get confined in space, everything gets just a little bit more complicated.

OK, but in the end – it’s finished.  In the end, I’m pretty happy.  I feel like I accomplished something.  I fixed something and made it better.  I feel human.

I wasn’t always like this.  I remember in my early adult years I would think:

Why can’t they just make toilets that don’t break?  For that matter, why not make a lawn that doesn’t need mowing.  Oh, how about clothes that don’t need washing?  All of this cleaning an fixing stuff is just taking away time from more important stuff.

That was the old me.  The new me doesn’t mind these chose so much.  Oh, I still get bothered sometimes.  When the lawn needs mowing and it’s super hot (or won’t stop raining) or when something breaks and you JUST KEEP MESSING UP.  Yes, those times are frustrating.

But I’ve come to accept that we live in a world that increases in entropy.  If you leave stuff alone, it will just mess up and eventually break.  What makes humans so awesome is that we can fight this tide of increasing disorder.  We fix things.  We clean things.  We are humans.

 

 

Peltier Cooler

I have this small wine-refrigerator that is both old and not working.  I don’t really need it, but it’s nice to keep extra beers and wine in there.

My idea is to get a peltier cooler and convert this from a compressor cooler to a solid state cooler.  Of course it won’t be as efficient or cold – but as long as it gets just a little bit cooler I will be happy.

I ordered some coolers online (they weren’t super expensive) and they seem to work. It requires 12 volts and up to 5 or 6 amps – so the power supply might be an issue (it seems many people use a computer ATX power supply).  Actually, you can just connect it to a D-cell battery and put your fingers on each side of the cooler and easily feel a temperature difference (great for demos).

With a temporary power supply, I put the cold side of the peltier on a big aluminum block and then I put a cpu heat sink on the hot side.  This didn’t work – but here is a picture.

IMG_4732.jpg

It turns out that the peltier cooler gets hot – but it keeps a temperature difference between the two sides.  So the key is to keep the hot side as cool as possible.  With this in mind, I switched it so that the hot side was on the block and there was nothing on the cool side.  I still didn’t work very well until I put some thermal paste between the peltier and the aluminum block for good thermal contact.

Here is what I get.

Pretty cool, right?

I will keep you updated.