# MacGyver Season 2 Episode 7 Science Notes: Duck Tap + Jack

Let me start off by saying that I mostly agree with Jack. There is a good chance that Ewoks eat people (human people). Why else would they put Luke and Han on those roasting sticks. It sure looks to me like they were going to roast them and then (logical next step) eat them.

Oh, in case you didn’t know. The original plan was to have some super intimidating creature that the Rebels first fear and then team up with. These creatures were going to be the wookiees. When George Lucas started Episode IV, he didn’t know if he would get to the last movie—and he really liked the wookiees. He decided to put one in as Chewbacca. That left the Ewoks in Episode VI. (see The Secret History of Star Wars)

MRE Hot Sauce Bomb

It’s sort of a bomb. Really, it’s supposed to be a type of tear gas. Of course an MRE is a “meal ready to eat”—but it’s even better to eat if you heat it up. Most MREs come with a chemical heater. It’s a small package that gets hot when water is added. Along with getting hot, it also produces a gas. This gas is the source of the bomb. All you need to do is to put the heater and water in an enclosed container and the interior pressure will eventually build up and explode.

For MacGyver’s version, he adds hot sauce. When the water bottle explodes, it spreads hot sauce everywhere. Yes, pepper spray is essentially hot sauce (but very hot hot sauce).

Tire tool slingshot

Really, there’s not much science here. MacGyver uses bungee cords to launch a tire tool (one of those things to remove wheel bolts) at a car. This would pretty much work, but it might be tough to get a good hit.

Jack Heart Pump

The “heart in a box” breaks. Instead of replacing the broken pump with a traditional pump, MacGyver uses Jack’s heart as the pump. It’s sort of funny.

Scooter Generator

Most generators are just some method to turn an electromagnetic coil to create electricity. You can use wind, water, steam, or yes—a gasoline engine. In this case, MacGyver connects a scooter to the generator. Boom. Power.

# MacGyver Season 2 Episode 5 Science Notes: Skull + Electromagnet

Decoration with syringe hydraulics

As they decorate for Halloween, the crew builds this skeleton that is controlled by syringes. The basic idea is to use a tube to connect two syringes (the big kind). Fill it with water. When you push or pull on one syringe, it makes the opposite thing happen with the other syringe since water is incompressible.

Here is a nice video showing how to make something like this.

Directional Antenna

In order to track down a dude, MacGyver builds a directional radio antenna. Well, actually he just combines a yagi antenna and a dish antenna—I’m not sure it would work like that, but it looks cool.

I don’t think I should go into the physics of a yagi—it might take a while to explain. However, I can say this: that old style TV antenna you had on your roof? That’s a yagi. It does have a directional dependance on amplitude. That means that if you point it one way, you will get a better signal than pointing it another way.

DIY Thermal Camera

How do you find people in a dark abandoned military base? What about a thermal camera? A “thermal” camera is just like a normal camera except that it’s different. Instead of detecting electromagnetic waves in the visible region (we often call this visible light), a thermal camera works in the infrared range. That’s why they are also called infrared (IR) cameras.

Normally, that wouldn’t help you see in the dark—except for one important thing. All objects radiate light. The wavelength of this light depends on the temperature of the object. For most of the objects you see around you, the wavelength of radiated light is in the infrared range. So, with an IR camera these objects are like their own little light bulb. You don’t need an external light source—the objects are the light source.

Let me show you an example. This is an image using the FLIR One—it’s an IR camera attachment for your smart phone (pretty cool). Here you can see the family dog in IR. There’s a bunch of cool stuff you can see, but I will just leave this post for you if you want to know more.

The first devices to produce an IR image (mostly) came about in the 1950s. They used a single sensor that scanned over an area to produce an image. It wasn’t fast and the sensor had to be cooled. But still it worked.

So, how could MacGyver make an IR camera? Step one would be to find one of these sensors—maybe lead sulfide detector. This detector just gives a voltage though and not an image. To get an image, you need to scan over the scene and then run that into a television or something. Here is an early sketch.

How far away could you detect a human? I tried this out using my kids and my FLIR One. Here’s what it looks like at a distance of 7 meters.

Just for fun, here is the image from the episode.

In the end, IR camera’s are pretty complex. Honestly, it’s amazing that we have something that does this on a phone.

Escaping a hyperbaric chamber

Samantha Cage has been placed in a closed hyperbaric chamber that’s being filled with water. A hyperbaric chamber is essentially a person-sized scuba tank. You can put someone in there and then increase the pressure. This can be useful for a person suffering from decompression sickness (from scuba diving).

Anyway, she’s trapped and needs to escape. MacGyver builds a captive bolt gun to break the window. Oh, that’s cool and all—but I have a better option to escape.

What if you sealed up the chamber to get her out? It sounds crazy, but it would work. Here’s the problem. In order to add water to the chamber, you either need to increase the interior pressure by adding high pressure water. Or—you can add water while letting some of the air out. The second method is much easier to do (since it just uses normal water). But this means there is either a valve that is open to let the air out or maybe there are some old and bad seals that let air out.

Now, if you seal off the chamber the water can’t come in. And if the water does indeed enter, it will increase the interior pressure. Hopefully the pressure will get high enough on the inside that Cage can add a little extra and bust out.

It’s just an idea.

Electromagnet Lift

Could an electromagnet actually lift something large? Absolutely. Have you not seen those giant electromagnets at the junk yard that lift cars? But what about a human? The human body doesn’t really have enough ferromagnetic material in it for this to work (unless you are Magneto). However, it’s at least plausible if that person has a steel plate implanted. Yes. It’s true that many metal implants are titanium. Also, the steel implants are stainless steel and some versions of stainless steel aren’t magnetic. But still—it’s possible.

An electromagnet is really just a coil of wire with current running through it. It’s not hard to make, here you can do it yourself.

But what about a HUGE electromagnet? If you want a super strong magnetic field, you need a GIANT electric current. It’s possible to get perhaps 10 amps out of a truck engine (from the alternator or the battery)—but that might not be enough. My suggestion is to get a bunch of car batteries together so that you can get the highest current possible. Of course this high current is going to make the wires hot, so don’t run it for too long.

# MacGyver Season 3 Episode 22 Science Notes: Mason + Cable + Choices

Season 3 finale—but don’t worry, MacGyver has been renewed for a 4th season. Boom. Now for some science.

Descender Device

MacGyver needs to get down an elevator cable—to do this, he builds a descender. The basic idea is to “grab” hold of the cable to produce enough friction that it supports a human. That keeps you from falling. Of course you also want to move down, there needs to be some method to “inch” your way down. The one MacGyver builds looks like this.

Here is an early sketch for a type of descender

Of course the problem is that the elevator cable is under tension and very thick. It’s really more like a pole than a rope. That’s why the design in the episode would work better.

These aren’t bad hacks—they are hacks from the Bad MacGyver (Mason). First, there is the cable cutter. This is just a bolt cutter connected to an electric motor. That should work.

The other one is the hydrochloric acid in the basement of a building around support pillars. So, would this work? Well, hydrochloric acid does indeed dissolve concrete and cement—it’s not super fast though. Everyone likes to think of acid as being that kind in the movie Alien. It’s not like that.

Of course a pillar isn’t just cement. It has steel rods in there too. But acid will eat through steel as well—again, it just takes a while. But you don’t have to completely dissolve the pillars to cause destruction. Just making them weak could do the job.

Oh, it’s a good thing the hydrochloric acid is in plastic barrels. It would melt steel barrels.

Atwood Machine

MacGyver’s plan is to connect one elevator to the one next to it. When the cable is cut, the two elevators will create an Atwood machine. This is of course a real physics problem.

The idea is to have two different masses connected by a string. This string then runs over a pulley. If the masses are different, the two masses will accelerate (one up and one down) with a constant acceleration. The key is that this acceleration will be much smaller than the acceleration of a free falling object. That’s a good thing since waaaaay back in the day, it was very difficult to measure the motion of an object with a large acceleration.

I think I will save the physics of an “Atwood Machine Problem” (no one really calls it that) for a later post. Instead, here is my calculation.

But wait! There’s more! This calculation would give you the tension in the cable, but once there is a tension the cable would stretch. How much the cable stretches depends on:

• Tension
• Cable length
• Cable diameter
• Type of material

So you see that the stretch really depends on two things—the material and the size of the cable. For the material dependence on stretch, we call this Young’s Modulus.

There is one more thing—maximum tension before a cable breaks. This also depends on the type of material and the shape of the cable. Here is a sample calculation.

Too bad MacGyver never got a chance to put these calculations into practice. Of course it’s Mason’s fault.

Recover Serial Number

It is possible to recover a serial number that’s scratched off a metal. Essentially, when the number is stamped into the metal there is a more than just a surface effect. The deeper metal is also changed in some way. Using acid, it’s possible show these differences and find this number. Yes, this is real.

For a circuit chip, the serial number is not likely to be stamped—it will be printed. Still, it’s entirely plausible that you could still recover some type of artifact.

# MacGyver Season 3 Episode 21 Science Notes: Treason + Heartbreak + Gum

Breaking Window Bars with a Bicycle

This is another classic MacGyver hack. There is a window with bars on the outside and Mac needs to get IN. Simple, just pull off the bars. Obviously you can’t do this with your hands, you need to build something.

I guess you would call this a hand-crank winch. That probably best describes what he builds. Actually, it’s a hand crank winch WITH a compound pulley. Here are a couple of pictures.

The main idea here is the same for ALL simple machines. It’s really about force, distance and work. Let’s start with a super basic definition of work (physics work).

$W=Fd$

In this expression (which isn’t technically correct—but that’s OK for now), W is the work, F is the force applied and d is the distance over which the force moves.

Now imagine I have a simple machine. I can put work into it and get work out of it. Assuming it is 100 percent efficient, the work in can’t be less than the work out (or you would get FREE ENERGY).

So, if you want to pull (or push) with a smaller force then you need to pull over a larger distance. For the output force, you need to have it move over a shorter distance to get a larger force.

With the winch, MacGyver turns a hand crank (part of the bike). If the garden hose (used for a rope) is wrapping around something with a smaller diameter, then for each rotation of the hand the rope will move a small distance. This is the key to a winch. Remember—smaller distance means larger force.

With the compound pulley, the same thing happens. By using multiple pulleys—you can make the pull force move over a larger distance thus increasing the output force.

Here is my initial diagram for how this might work.

Spark Gap Generator

You don’t get to see much detail here—so let me just explain the idea behind a spark gap generator.

First, I guess I should say what it is used for. Originally, a spark gap was a radio transmitter. It turns out that although it’s simple to build, you can only use one at a time because they don’t really use channels. In the case of MacGyver, he is using a spark gap to jam a phone signal (to prevent data transfer).

All of the wireless data works by broadcasting and receiving electromagnetic waves. Radio, microwave, visible light, x-rays…these are all electromagnetic waves (but with different wavelengths). Still, they are electromagnetic waves.

So, what about this spark gap? The idea is to create a repeating spark across some small gap. This spark is a very violent (electromagnetically speaking) event. It has accelerating electric charges which create EM waves. These EM waves are high enough intensity that they can make it such that other (more well behaved) devices can’t send or receive a signal.

But how do you make one of these spark gap generators? Really, you just need a battery and some wires. If you use the wires and battery you can create an electromagnet. That doesn’t make a spark, but if you can turn it on and off really quickly, then it will indeed make a spark. I built one using a moving metal switch. When the electromagnet is on, it pulls the metal and turns off the switch. Once the switch is off, the metal is no longer attracted to the electromagnet and it moves back in place to turn the electric current on again. This just repeats to make the spark.

Here is a video.

Here are some more details on this.

Oh, here is another way to make one of these spark gap generators.

Gum Wrapper Switch

The key to this episode (it’s in the title) is gum. MacGyver activates the spark gap by taking out a piece of gum. How would this work?

The purpose of a switch is to do something such that two wires are connected. In this case, the two ends of the circuit could be the foil wrappers for two pieces of gum. If you put an insulator (gum) in between them, then the circuit will be closed. Pull the gum out and then two foil pieces will touch and complete the circuit.

Here is a diagram I created for this.

# MacGyver Season 3 Episode 20 Science Notes: No-Go + High-Voltage + Rescue

There aren’t a bunch of hacks in this episode—so that means I can just write about whatever I want.

This is just classic MacGyver stuff. I really don’t have anything to add.

High Voltage Power Lines

Now we are talking. Why are these power lines high voltage? To answer this question, we need to first think about three things: power, voltage, current.

Let’s start with power. This is the rate of energy change (or in this case, energy loss). For an electrical circuit, the power loss is equal to the product of voltage and current.

$P = I\Delta V$

But wait! There is also a relationship between voltage and current.

$\Delta V = IR$

Where R is the resistance (in Ohms) of some element. Substituting this definition into the power definition:

$P = I^2R$

So, here is your answer. You get more power loss with a greater current. That means the best option is to have low current power lines. But if you want to transmit power—you have to make up for this with high voltage. Boom. There’s your answer. OK, technically these power lines are alternating current and voltage, but the main idea still works.

Next question. What happens if you touch a high voltage line. The answer: not much really.

Yes, if you touch a high voltage line AND something else—like the ground then you will get zapped. The thing that really messes up humans is an electric current running through them. If you just touch one line and nothing else, there is no complete circuit. With no complete circuit, there is no electric current. Oh, this is why those birds can sit on power lines. As long as they only touch that one line, they are fine.

Belay from a lock

The key to a belay is friction. This is actually a pretty cool thing—the more turns a rope has around something (like a post), the greater the friction. You can control the amount of friction between the pole (or padlock in this case) and the rope by slightly varying the amount of rope around the pole.

I think I need to do an experiment to show this—maybe I will do that later. In the meantime, here is a nice tutorial on belays.

Oh, but what if MacGyver wanted to express his anxiety about heights by calculating the impact force if he fell. His calculation might look something like this.

Motorcycle Jump

MacGyver and Desi need to jump a fence with motorcycles. Here’s what he might calculate to find the minimum motorcycle speed to make the jump.

# MacGyver Season 3 Episode 19 Science Notes: Friends + Enemies + Border

Crane and winch

The problem with a sinkhole is that the sides of the hole are unstable. You can’t just climb up the side or lower a rope down the side. This would just cause further collapse.

The answer is to get a crane. Something that sticks out over the edge of the hole, but doesn’t interact with the hole. Really, this is mostly just a nice build—but there is one physics thing to discuss.

You can’t just get a pole and stick it out from the truck and expect that pole to lift any weight of significance. It will bend or break. You need some type of structure to allow the crane to exert a torque on the end.

Here are two ways you could do that. First, you could make a type of truss. It might look something like this:

The triangle structure in the truss makes the whole thing rigid. Also, it allows multiple forces on the support end. There needs to be a force that will exert a torque to counteract the torque from the load.

The second method is to use a cable. I’m sure there is a technical term for this, but I’m just going to call it a cable. It would look like this.

I just realized that there was a mistake on the forces for the truss diagram. But you still get the idea.

Bonus, here is my initial diagram for this situation.

What about the tire and rope thing? Yes, this should work. MacGyver takes the rope and wraps it around the tire. This means that the truck’s engine can be the power to lift the humans out of the hole.

DIY Furnace

MacGyver needs to fashion a vascular clamp from some normal clamps. To do this, he builds a mini furnace. This is real. Actually, I built one of these with my daughter so that we could melt aluminum. Here is the video we started with. Note: this is awesome, but also dangerous.

This actually works. There is something amazing about melting metal with charcoal. We started off with a charcoal furnace and an old vacuum cleaner to blow in air. It works, but it goes through a bunch of charcoal really quickly. So, we switched to a propane version—this is much easier.

Bonus—here is my furnace diagram for the show.

Flash Bang

I don’t want to write about the flash bangs—but I should say there is a legitimate basis for this. I just don’t want to tell you.

# MacGyver Season 2 Episode 4 Science Notes: X-Ray + Penny

Hydraulic Hammer

OK, it’s not really a hammer. It’s more like a pressure gun. MacGyver hooks up a pressured line from a water heater to a tube with a rod in it. When the pressure is released, it shoots the rod and hits the door handle to knock it out. That’s great.

If you want it to “hammer” back and forth, you need to do something different. Here is a very basic design.

There is still a tube with a rod, but there are two differences. First, there is a hole on the side of the tube. As the rod moves forward (due to the pressure from the hose), it eventually gets to the part where the side hole is exposed. This would allow the pressure to escape and the rod would stop moving forward.

The other feature is a spring. One side of the spring is mounted to the outside tube and the other to the inside rod (yes, there needs to be a small slit in the tube). This spring will pull the rod back into place once the pressure escapes.

I really don’t know if this would work.

Finding Location with Sound.

This one was tough—but fun. How can MacGyver use evidence he collects to go back and figure out his location? In this case, he uses sound.

In air, sound travels at a finite speed. Technically, the speed of sound depends on the temperature of the air—but using a value of 340 meters per second is a reasonable value.

Since this sound speed is finite, it takes some finite amount of time for this sound to travel over a distance. But of course you already know this because you have seen lightning and heard the thunder. The light part of this lightning strike travels at the speed of light (which is really, really fast). However, the sound part of the strike travels much slower. This means that you see the lightning and then hear the thunder later. The farther away you are from the lightning strike, the bigger the time difference between these two signals.

For MacGyver’s case, he is going to use two sounds that start from different distances and at different times, but reach him (he hears them) at the same time. In this case the sounds are from church bells and a fire station. It’s sort of like the opposite of the lightning problem except that it’s totally different.

So, here is what he knows.

• Church bells every half hour.
• Fire station alarm went off at 1:29 and 58 seconds.

That means the sound from the church bells traveled for 2 more seconds than the fire station sound. How far away is MacGyver from the 2 sources? Yes, this is a more difficult problem—but it’s not impossible.

This is what MacGyver writes on the board to solve this.

Now for fun, here is my original solution.

Isn’t that fun? Well, it is for me. Oh, what about the two points? You can think of this problem as two expanding circles. Each circle represents a sound and the circle’s radius increases at a rate equal to the speed of sound. So, one circle is going to be bigger than the other one (because that sound was created first). We are looking for the places where the two circles intersect. Yes, there are two of these locations. MacGyver picks the location based on the direction of water flow in the sewer.

You know, I really should make a python animation for this problem. Maybe I will do that soon. Oh, one final note. For my solution above, I recreated the calculation so that it would have the correct values. At the time, I was at my son’s soccer practice. So this is a picture of my notes as they are sitting on the seat of the car. True.

X-Ray Fluorescence

It’s real. The basic idea is to use x-rays on the film. These x-rays excite some of the atoms in the film such that they fluoresce and produce infrared light. You can’t see the IR light, but a video camera can.

It’s something like this—a technique that is used to look at different layers in paintings.

https://www.livescience.com/13499-hidden-painting-features-xrays-110331.html

As a bonus, I made a short video explaining x-ray fluorescence.

# MacGyver Season 3 Episode 18 Science Notes: Murdoc + Helman + Hit

There’s really only two MacGyver hacks in this episode—but wait! Don’t be upset, it’s a good thing. First, it happens to be a great episode. Second, when you don’t have a set number of hacks in an episode it just feels like the story uses these hacks rather than revolve around them.

Overall, it was a great episode.

One way mirror.

This wasn’t a MacGyver hack, but it as funny and there is some nice science here. So, what is a one way mirror? Also, Murdoc has a point. Shouldn’t it be a two way mirror? Actually, there are several names for these things:

• One way mirror.
• Two way mirror.
• One way glass.
• Half silvered mirror.
• Semi-transparent mirror.

I guess you can call it whatever you want. But how does it work? There are a few important things to go over. First—how do we see things? Suppose there is a pencil on a table. If you see that pencil, it’s because light reflects off that pencil and then enters your eyes. Here is a diagram (from my post on 5 Things Every Human Should Know About Light).

Second—how does a window work? In the most basic form, a window could just be a piece of glass. When light hits glass, two things happen. Some of the light is transmitted and some of the light is reflected. Yes, this pretty much always happens. OK, I lied. There are some cases where all the light is transmitted and other cases where all is reflected.

I can prove this to you. If you are inside a house on a sunny day, you can see outside but other people can’t see in. The problem is that the outside stuff is so bright that the reflected light is way more than the light coming through (from the inside) and you can’t see it. Here is a diagram (from this old post of mine).

Now back to the “one way mirror”. The key is to have the room with the observers darker than the room with the people you want to watch.

Skateboard with a pulley.

There is a door, but it’s trapped. It’s a trapped-door. Get it? OK, so MacGyver needs to bust this down but without people nearby in case it explodes (it does explode). He takes the battering ram weight and puts it on a skateboard. Then he run some string over a couple of pulleys so that he can get this thing up to speed and smash into the door.

Here is a diagram (from my show notes) to see how you would set this up.

The key to a pulley system is to set it up so that the distance the object moves is different than the distance the person pulls. In fact, this is the key idea to all simple machines (a compound pulley is indeed a simple machine).

In the diagram above, if Mac pulls the bottom pulley (this is a top view) one meter, then there would need to be two meters of string move that way (since the string is doubled over). That means the skate-board and battering ram would move 2 meters for this 1 meter of pull.

Yes, the skate board would move twice as fast as MacGyver. But you don’t get something for nothing. Although he only moves 1 meter for the 2 of the board, there would be twice the force on MacGyver. This is how simple machines work.

Slowing down a car with a winch.

MacGyver grabs the winch on the truck and then jumps to the truck with Murdoc. He wraps the cable around a post and then Oversight slams on the brakes. Both cars stop.

Yes, the friction from the rear truck would indeed slow down the other car (if not stop it). However, since the cable is attached to the side of Murdoc’s truck, the force from the cable will also turn that truck. Once it get’s turn too much, it can’t even drive straight. Now both trucks are essentially sliding with rubber wheel interacting with the road. That’s why it stops.

# MacGyver Season 2 Episode 3 Science Notes: Roulette Wheel + Wire

Is there a better MacGyver image than his radio build at the beginning of the episode? I think not. Here is an image.

Could you actually build a radio from a snow mobile? I think yes. Really, radios aren’t actually that complicated. The only difficult part would be building an amplifier so that the signal generated from a voice is powerful enough to be detected by someone’s radio. If the snow mobile had any kind of radio (like for listening), you would have all the parts you would need.

Stun gun on slot machine

They call these hand held zap things stun guns, but they don’t shoot. You just have to hold them up to someone to shock them.

MacGyver needs a distraction so he takes the stun gun and uses it on a slot machine. After that, the guy playing wins.

Is this even possible? Possible, yes. Likely, no. The stun gun has high voltage that creates sparks. These sparks can damage electronic equipment—especially the super tiny transistors in a computer chip. So, it’s possible that the stun gun does something to cause a win.

However, these slot machines are built with tampering in mind. They need to be able to resist humans messing around with them to win. So, I doubt this would work. Also, if MacGyver zaps that outside of the machine it’s probably grounded. This means that the electric current that gets into the case of the slot machine will just go around all the electrical components.

You probably have a better chance of winning on the slot machine than cheating on it.

Iris scanner hack

In order to get through an iris scanner on a door, Jack gets a close up picture of the target’s eye. Then Bozer prints out a fake lens to wear over the eye. Could this work? It’s possible.

In fact, check this out. Someone did the same thing with the Samsung Galaxy S8.

Handheld Cellphone Stingray

A cellphone stingray is a device that acts like a cell tower. Cell phones connect to it thinking that it’s just a tower—but blam, it’s actually another computer.

Of course the details are complicated (which means I don’t really understand them), but you would need some type of antenna. Jack has a tiny antenna in his cuff that has to get close enough to the target’s phone. I think this is plausible. At least it would give Riley a chance to get into the phone and steal some codes.

Magnetic Detector

Also known as a compass. MacGyver is trying to find a magnetic switch for a hidden door. He grabs a bit of metal (hopefully it’s ferromagnetic steel) along with a magnetic bottle opener.

The basic idea is that a metal like steel (most steel) has magnetic domains. When these domains are lined up, the material will act like a magnet. You can line up the domains by rubbing the steel with a magnet. Like this.

If the magnetized steel can float, it will rotate and point in the direction of an external magnetic field—either from the Earth or from that magnetic door switch.

OK, one small issue. In the episode it shows MacGyver rubbing the steel back and forth. You really just want to rub it one way. I think it would still work though. Oh, also many of those magnets like the one on the bottle opener have weird domains. They aren’t just like a plain north and south of a bar magnet, but it still might work.

Vacuum Cleaner Spider-Man

This is awesome (and mostly real).

Here’s how it works. The vacuum cleaner works by pulling air out of a region. If you put a vacuum cleaner over carpet, the air flow goes from the carpet to the vacuum cleaner (basically with just a super powerful fan). When the air moves in this manner, it often picks up other stuff—like dirt.

MacGyver has this vacuum hooked up to some metal tray covers. When the air is pulled from these covers, the air pressure inside the covers decreases. That means that the external pressure (due to the Earth’s atmosphere) will push the covers onto the glass wall.

Actually, this force from the atmospheric pressure can be quite large. The pressure is $10^5\text{ N/m}^2$. So if the pressure inside the covers is just half an atmosphere with a radius of 10 cm, then the net force (for the two covers) would be:

$F = PA=(0.5\text{ N/m}^2)(2)(\pi (.1\text{ m})^2) = 3141 \text{ N}$

That’s some serious force. But wait! This is not the force that supports MacGyver. In fact, it is the frictional force between the cover and glass that keeps him from falling. The frictional force is an interaction between two surfaces that acts parallel to the surface. It depends on two things:

• The types of materials interacting.
• The magnitude of the force that pushes these two surfaces together.

If you push two surfaces together really hard, there will be a greater frictional force. So, this force from the vacuum cleaner exerts a force that increases the frictional force and this frictional force allows MacGyver to climb like Spider-Man.

Here is something similar with a guy that hangs from an overhang with a vacuum cleaner. Pretty cool.

Shrinking metal

This is real (based on something real). Yes, you can actually make metal things smaller. Here is a great video from Physics Girl (Dianna Cowern) that shows how this works.

The basic idea is to create a HUGE electric current very quickly. This large change in current can create a very high change in magnetic fields. When you put metal in this high changing magnetic field, it induces an electric current in the object. This induced current creates a magnetic field that interacts with the external magnetic field in such a way that the device gets squished. It’s awesome. Oh, when I say “a large change in magnetic field”, I am actually talking about the time derivative of the magnetic flux.

So, what do you need to make this coin shrink thing work? You just need super high current super fast. The best way to do this is to charge up some big capacitors and then discharge them through some wires. That’s essentially what MacGyver does.

The biggest problem is his capacitor. He builds one using two roulette wheels. Like this.

Yes. Any two metal devices can create a capacitor—but you want one with a large surface area and very close together. If you turned the two tables around so the flat side was close to the other one, it would be better—but it’s still a capacitor (but not really big enough for this job). Still, the idea is solid.

# MacGyver Season 2 Episode 1 Science Notes: DIY or DIE

I’m kicking myself. I should have been writing these MacGyver notes for each episode as they aired on TV. But no. I had to make things more complicated. Well, here I am—starting the notes for season 2.

Let’s just jump in. Note: there’s some pretty good stuff in this one.

MacGyver takes a button from his shirt and breaks it in half. From this half button he sharpens the edge so that it can cut through a rope.

I wouldn’t normally include this one in the blog since there’s not much science to talk about—but I’m just excited.

Flare-based harpoon and winch.

MacGyver takes a metal rod and puts it in an empty dip stick tube from an engine. He adds the powder from a road flare to act as a propellant. This would then launch the improvised harpoon forward.

Once the harpoon is stuck into a fleeing car, Mac wraps the cable around the horizontal axle on the sidecar to a motorcycle. As the axle spins, the cable wraps around it and pulls the motorcycle closer to the car.

Mini gun as a starter motor.

They need a car. MacGyver finds one—but it’s missing a starter motor. Really, there is nothing super special about a starter motor. It’s just a DC motor that is strong enough to turn over the engine so that it can turn itself (using gasoline).

The mini gun also uses an electric motor. In this case, the motor spins a combination of gun barrels so that the fire rate can be higher than a normal machine gun.

Could you use one motor for another application? Theoretically, yes. The only tough part might be mounting the motor (which MacGyver does with some wire—wire is often better than duck tape). The other problem is making sure the gears on the motor match up with the gears on the car to turn over the motor—but it’s still possible.

Run up a wall with a pole

Sometimes, there are hacks that look too crazy to be true—but in fact would totally work. Here is an example of such a hack.

MacGyver and friends take a long pole. MacGyver gets on one end near a wall and the other two push the pole towards the wall. This allows MacGyver to walk up the wall.

But wait! Here is a video of this trick being used in real life by a Vietnamese SWAT team.

Here is my super short explanation.

• If you push someone against a vertical wall, there will be a frictional force pushing UP.
• If the push is great enough, this upward frictional force can be equal to the gravitational force.
• Boom. That means a person can walk up a wall.

Here is a force diagram of that situation.

Oh, I also made a video to show you how this works.

Cell phone in a soccer ball.

Ok, you can put a camera in a ball and kick it through a window. Not really much of a hack, but clever.

Improvised diver propulsion vehicle.

MacGyver needs to get through a submerged passage—it’s long enough that he can’t swim the whole way. This means he needs some scuba stuff. In particular, he needs the following:

• Some type of air supply with a regulator.
• A mask and some type of mouthpiece to breath.
• A light.
• A DPV—diver propulsion vehicle.

Please forgive me, but I’m going to go over more detail in this case that you would like. I can’t help it. MacGyver is basically cave diving—this is something that I used to do quite a bit.

Just to show you what that was like, here is an older picture of me. It’s not cave diving, but it’s using all of the same gear (it was practice).

Let’s start with the scuba gear. MacGyver doesn’t have a regular scuba tank, so he uses an oxygen tank used for welding. You don’t normally want to use oxygen for scuba—you want to use air (which is only 21% oxygen). You see, oxygen is actually toxic. If you breath oxygen at high pressure, it can do bad stuff to you. Fortunately, MacGyver is going to use this at very shallow depths—he should be fine. Also, he won’t need to much gas as you consume much more at greater depths (for open circuit systems like scuba).

What is a regulator? Suppose you have a pressurized tank at 1000 psi. You can’t really breath air (or any gas) at that pressure (although there are some tricks—ask me later and I can tell you about this). That’s where the regulator comes in. It takes pressure from the tank and reduces it to the ambient pressure. That’s really important. It has to deliver the pressure at the same pressure around the human. If it was too low, you wouldn’t be able to expand your lungs and breath.

Luckily, they have regulators for welding stuff too. You need a second regulator to let air out only when you breath—but it’s possible to build one of these (they are much simpler).

Now for the DPV. These things are very useful in cave diving. How are you supposed to get 5,000 feet back in a cave if you have to swim the whole way? The early DPV (or scooters as we called them) were essentially trolling motors from a bass fishing boat connected to a battery.

Just about any electric motor with a battery could work. Ideally, the motor should be sealed so it can run underwater—but it doesn’t have to be perfect. It only has to work for a short time.

I really like the scooter in the episode. It really looks like a home built scooter.

OK, you can’t see it too well in that image—just trust me. Or better yet, watch the episode.

I also like how MacGyver side mounts his tank. Even if you have done normal scuba diving, you might be surprised at how these tanks behave underwater. Just because they are heavy out of water doesn’t mean they will pull you down underwater. Very often we would bring extra tanks (stage bottles) in a cave and carry them on our side just like MacGyver did.

Parkour Wall Jump.

MacGyver gets to run up a wall twice in this episode. Just like the wall run with the pole, this case also uses friction. It’s your classic parkour wall run-jump.

If you run towards a wall and push yourself back, there is a force between you and the wall. The faster you run, the greater the force. If this force is great enough, there will be a large enough upward frictional force so that you can get an extra upward jump.

That’s exactly what MacGyver does to get out of the tunnel. Here is a more detailed WIRED post on this wall jump.