MacGyver Season 4 Episode 4 Science Notes: Windmill + Acetone + Celluloid + Firing Pin

Egg Drop

It’s not really a normal “MacGyver-hack”, but the egg drop does have a bunch of physics in it. Oh, you’ve never heard of this? Well, it’s a fairly common activity in science classes. Basically students build “something” around an egg so that they can drop it from some particular height and the egg won’t break.

There are a whole bunch of extra rules—like “no parachutes” and “no rockets” and stuff like that. It’s all good fun (mostly). But what about the physics?

Most stuff that breaks on impact are the result of high accelerations from differential forces. If the egg (or any object) is being pushed on one side more than the other with some force (like from the floor), this differential force breaks the material.

Now for some real physics—the Momentum Principle. This says that the net force on an object is equal to the time rate of change of momentum where the momentum is the product of an object’s mass and velocity.

\vec{F}_\text{net} = \frac{\Delta \vec{p}}{\Delta t}

\vec{p} = m\vec{v}

If an egg is going to hit the ground, you know the change in momentum. It’s going to have some initial value and then it will stop. You can’t change this. But you CAN change the time. Let’s write the Momentum Principle in a different way:

\Delta \vec{p} =\vec{F}_\text{net}\Delta t

So, how do we get a particular change in momentum? You can think of two extreme cases:

  • You can have a VERY LARGE FORCE with a very small time interval.
  • You can have a very small force with a VERY LARGE TIME INTERVAL.

Of course you could go somewhere between these two—but you get my point. This is how the egg drop works. You want to build something that INCREASES the impact time so that you get a smaller force.

Why study science?

MacGyver is right. Scientific thinking is problem solving and critical thinking. These are good in any field—not just physics or working at a “think tank”. So, yes science is good for you. But that’s not why you should study it.

Science is one of the things that makes us human. Some of the other human things that we do: art, music, literature, sports, writing and video games (maybe). So, humans should study things that makes us human. That’s why you should take physics (and art).

One last science comment. The Physics Honor Society has this great page on hidden physicists. These are people with degrees in physics that have jobs that might not be labeled as “physicist”. It’s great.

Compound Lever

The keys to all simple machines are force and the distance a force moves. If you apply a force over a greater distance, you can produce a larger amount of energy (to lift stuff or something). This is how a basic lever works. You put a stick on a pivot.

The compound lever is just a way to get the push down force to move over a greater distance. Basically, it’s a lever connected to a lever. It’s lever-inception.

Hoist Lift

Here’s another way to lift something heavy—like a WWII bomb. You can use a hoist. It’s essentially the same idea as a lever except that stuff is hanging from it.

Tri-wheel Stair Climber

This is real.

Of course you can make it more MacGyver-ed by adding a power source. Mac uses some cordless drills to assist with the climb. Oh, you don’t think that would work? Well, if you have a big enough battery you can move anything up the stairs—it just might not be very fast.

Bomb Egg Drop

Putting a bomb in a box with bungees might work. As the bomb-box hits the ground, the bungees will stretch and INCREASE the time that it takes the bomb to stop—thus DECREASING the impact force. It doesn’t matter if it’s a bomb or an egg, it’s the same physics.

OK, you want to win at the egg drop competition at school? Here’s a great video from Mark Rober looking at some of the best egg drop options.

MacGyver Season 4 Episode 3 Science Notes: Kid + Plane + Cable + Truck

Can you hear a radio transmission through a fan?

Answer: it’s possible.

So, here’s the deal. MacGyver needs to communicate with this kid on a nearby plane—but he doesn’t have the radio speaker turned on. How do you tell someone to turn on the speaker if they don’t turn on the speaker?

There are two parts to this answer. First, you need to build an AM radio transmitter. This isn’t too difficult—especially for MacGyver and all the stuff he has in the Phoenix jet. Here is a build similar to the one in the show.

Fine. But what about hearing it in a fan? The short answer is that the fan can act like a foxhole radio. Yes, that’s a real thing. It’s a type of radio that soldiers could build using some basic items. But the key to all of this is the diode. A diode is basically a one-way valve for electric current (I said “basically”—so, don’t freak out about that definition). Why do you need a diode? It’s because you can’t “hear” radio frequencies.

Let’s look at AM radios (because FM is a bit more complicated). AM radio stations broadcast at different frequencies for different channels. These frequencies range from 500 kHz to about 1500 kHz. But if you just convert these electromagnetic waves into sound, you wouldn’t hear anything. Humans can only detect frequencies up to about 20 kHz. So, how do you fix this?

The answer is amplitude modulation (the A and M of AM radio). Here is an example of how this would work. Suppose I have a radio frequency of 3333 Hz (I just mostly randomly picked that value to make a pretty graph). Imagine this radio signal is just a cosine function that oscillates with that frequency. Now suppose that I constantly change the amplitude of this radio signal. The amplitude ALSO changes with some frequency—let’s say this amplitude frequency is 150 Hz (typical human voice frequency). Here’s what that would look like (here is the code if you want it).

But this won’t work. You can’t “hear” the 150 Hz signal—the problem is that the average of the AM signal is zero. It goes up as much as it goes down. It won’t work. That’s where you need a diode. This diode only allows the receiving signal to go “one way”. Here’s what that same AM signal looks like when you put a diode in.

Now for that diode. You could use a diode—or an LED light (which is a diode). Old crystal radios use a crystal mineral. If you don’t have that, you could use a pencil with a razor blade. Apparently, this kind of connection acts like a diode. Oh, you could also do this with the metal connection in the brushes of an electric motor—like in a fan.

Here is a story about a guy that thinks he’s crazy because he hears voices in his fan. I guess it’s true. Also, there is the famous (but maybe not true) story of Lucille Ball hearing Japanese spy radios through the fillings in her teeth. Here is the Snopes link for that.

One last comment. If you think “oh, this is awesome—I’m going to go listen to a radio station with my fan.” Nope. It’s probably not going to happen. You need a fairly strong AM radio signal that is tuned to your untunable fan. On top of that—the brushes in the motor of the fan have to be JUST RIGHT for it to work. It’s still plausible.


A defibrillator uses electrical currents to do something with the electrical nerve signals to the heart. I guess they can trick the heart into restarting if it has stopped. Fine—but how do you build one (note: don’t build one)?

Of course as with most things (especially dealing with living humans) this can get tricky. You want to run electrical current through the heart area, but not too high. Also, it’s probably best to have an alternating current—it’s complicated.

The simplest (and oldest) designs use a DC battery along with an inductor and a capacitor to make an oscillating electric current. MacGyver should be able to use the DC power from the plane as the “battery”. If you want to start with a higher voltage, you could charge up some capacitors and then reconnect them in series to pretty much get whatever voltage you want. The inductor shouldn’t be too hard to find either.

Landing electromagnet

Electromagnets are real. I guess you already knew that. The basic idea is that an electric current creates a magnetic field. If you make the wire into a coil, the magnetic field due to each loop will add together to make an even stronger overall field. Oh, more current is better.

But would this work in real life? Of course it depends on many things. The most important thing is the current. How much electrical current could you get out of an airplane?

I’ll be honest—calculating the current needed for an electromagnet is really tough. The magnetic force depends on the type of material being attracted (probably steel), the distance, the size of the coil, and the current. But still, I think you could get at least something like 1000 Newtons (a little bit more than the weight of a person). This might be enough to help a small airplane stick to the top of a truck. It’s plausible.

But let me just leave you with the BEST use of an electromagnet. Allen Pan made this AWESOME version of Thor’s hammer. It uses an electromagnet and a thumb sensor so that only Allen (who is obviously worthy) can pick it up.

MacGyver Season 4 Episode 2 Science Notes: Red Cell + Quantum + Cold + Committed

Let’s do this.

Metamaterials and Invisible Cloaks

Of course, this is not a MacGyver hack—but it is some science stuff. So, what is a metamaterial? It sounds cool—and it is, but it’s a very broad term. Usually when we say “metamaterial”, we mean some type of engineered structure that’s made of more than one thing.

What about invisible cloaks? The idea here is to use some type of metamaterial to interact with light using a negative index of refraction. Normally, when light interacts with materials there will be an apparent bend in the light ray as it makes a transition between materials. This bend in light is called refraction.

You see refraction all the time. Here’s an example of a pencil in a glass of water.

When light goes into the water, it bends a bit towards a line that’s perpendicular to the surface of the interface. That’s normal. If you had a negative index of refraction then the light would bend PAST this normal line. You don’t normally see that except with special materials—in fact we can really only get this to work with light in the microwave wavelengths (not for visible light).

But what does this have to do with invisibility cloaks? There’s a bunch of stuff to explain here—so, I’m just going to go with a very basic idea. First, in order to see something light has to reflect off that object and then enter your eye. That’s why you can see anything in a room with no light—there’s no reflection.

So, one way to make an object invisible is to bend the light around it. Suppose I have an apple with an invisible cloak around it. If I could trace a light ray around it, it might look like this.

But how do you make light do that? That’s the tough part—the idea is that you can do this with some type of special material (a metamaterial). You might not have that stuff, but you can make something similar with some mirrors. Check this out.

Quantum Computing

Here is my super short description of quantum computing. Current computers use binary numbers. Essentially, these are voltage signals. It’s either some positive voltage (1) or zero voltage (0). From this you can make logic gates and store data and play cat videos on the internet.

A quantum computer uses qubits that can be 1, 0 or a combination of 1 and 0 (that’s the quantum part). OK, now here’s a much better explanation.

Cold Containment Unit

How do you keep cold stuff cold? Really, you just need some type of thermal insulator. Yes, your jacket would work—so would a cooler for your drinks. But for super cold stuff, you need something a little more. One of the most common methods is to use a vacuum. If you have two containers with a space in between them (with no air), then it makes a great insulator.

What about making some cold stuff? It turns out that you can get really cold liquid from a can of compressed air (the kind you use to clean your keyboard).

Check this out.

Picture of an eye for a retinal scan

Can you take a picture of someone’s eye and then use that to fool a retina scan? Probably not, but it might be plausible.

Lojack Emulator

In order to throw some baddies off their track, MacGyver makes a lojack emulator and puts it in a teddy bear. It’s plausible. But what is Lojack? Here—this is good.

Drilling tool

MacGyver needs to drill through some rock. They don’t show the build, but there are plenty of parts around. Really, he would just need some type of electric motor—after that, pretty much any thing could work as a drill bit.


In order to get through a super old tunnel, Mac needs to breath (there’s not really any fresh air there). The answer is a rebreather. The basic idea is to use a chemical carbon dioxide scrubber that pulls the CO2 out of his exhaled air. You just need some tubes and stuff as well as the scrubber. I bet he could find the scrubber stuff near by.

MacGyver Season 4 Episode 1 Science Notes: Fire + Ashes + Legacy = Phoenix

Wow. It’s back. Finally, season 4 has started. I’m actually more pumped up than I thought I would be. Also, I’m ready to get back to my science notes.

Oh, one non-science comment. I think the Russ Taylor (played by Henry Ian Cusik) character turned out really nice. It was difficult for me to picture this guy just from the script. Henry did a great job.

Now for some science.

Professor MacGyver

At the beginning of the episode, we see MacGyver teaching a university class. At least once, they say that he is “professor” MacGyver. Is this possible? Could he be a professor? Could he even teach a university class?

OK, some background. Remember that Angus was a student at MIT before he dropped out to do bomb stuff in the Army. So, he probably doesn’t have a college degree—but it’s not clear. It’s also possible that he picked up some extra courses here and there to finish and graduate. It’s also very plausible that someone in the Phoenix Foundation just said “poof”—now you have an engineering degree. You know, they seem like the type that would do that stuff.

But what about the “professor” part. Oh, I guess I should add (in case you didn’t know) that I have a PhD in physics from North Carolina State University (Go Wolfpack). I’m also an Associate Professor of Physics at Southeastern Louisiana University. So, I kind of know some stuff about this.

There are actually multiple uses of “professor”. It can be used fairly generically to just mean some type of educator—this is common at the university level. But in terms of academic rank, you have the following titles (there are variations in these from place to place).

  • Instructor. This is a primarily teaching position. Most instructors have either a Master’s degree or a PhD.
  • Visiting Assistant Professor. This is almost always a PhD position for a faculty to come in and work on some research project temporarily. It can sometimes lead to a permanent position.
  • Assistant Professor. This is the first step in “tenure track”. When a person gets this rank, they will work for 5-6 years and then apply for tenure (and usually promotion to the next rank).
  • Associate Professor. This is the rank obtained after tenure. Oh, just to be clear—tenure is a method to give faculty the job security so that they can take chances on research and teaching that might not work out so well. Yes, sometimes that means the faculty just does nothing. No, they are not fire-proof. You can fire someone with tenure, it’s just not very easy.
  • Full Professor. This is just a rank higher than the two Ass-profs (I like to say that).

So, in this episode—it’s probably the generic sense of “professor” that is being used. It’s not very likely that MacGyver has the rank of Full Professor.

But what about teaching a class? Can anyone do that? Probably—yes. Most universities have a minimum requirement of 15 hours of graduate course credit in the field of the class. So, if you want to teach introductory physics you would need probably 5 graduate level courses that you had passed. This is about the same number of courses required to get a Master’s degree in physics (some variations apply).

Some universities also make exceptions for temporary faculty to teach courses. Either in an emergency situation (need some one the day before classes start) or to bring in an expert. Non-qualified experts are often used in fields like journalism (by non-qualified I mean they don’t have the degree requirements).

Now back to MacGyver. I’m going to say that at the end of Season 3, Phoenix Foundation just fixed his transcript. Boom. Easy.

Equations on the boards

Again, not really a MacGyver-hack, but I want to at least mention these equations. The first board is in the lecture hall. There’s a bunch of stuff on there—and it’s not all related.

The one part that I like the most is the stuff on the lower right. These are the tree physics representations of a ball moving vertically with a gravitational force. These three methods are:

  • Newtonian Mechanics
  • Lagrangian Mechanics
  • Hamiltonian Mechanics

Here’s an older post describing these three methods.

What about the other board? There are a bunch of equations on a white board in MacGyver’s place. Russ quickly just erases them—because that’s what he does. But what are these equations? If you look carefully, you can see the Greek symbol \psi (pronounced psi). This is used to represent the wave function in quantum mechanics.

Potassium in Water

Wow. We are still in the first few minutes of the episode. I think I was just excited to write about MacGyver and science such that I got a little out of control. I’m sorry about that.

For this “hack”, Professor MacGyver is trying to get the attention of his students. Simple solution—put some potassium in water. Seriously, don’t ever do this. The stuff on the left side of the periodic table does bad stuff in water. That means Lithium, Sodium, Potassium…they all make fire and then explode. Check it out.

It would be a lot louder and quicker than you saw in the show. Something would break.

Low tech photocopier

How do you copy someone’s hand written notes without a phone camera or an actual photocopier? How about using something hot? If you put a blank piece of paper next to the paper with ink on it, you could be able to partially make an impression on the blank paper. It would be something like this.

Let’s assume that the heat thing doesn’t fully work (it didn’t work perfectly in the video above). Maybe MacGyver needs to add a little something extra to make the copy readable. It’s plausible that he would need some acid to interact with the tiny bits of ink on the paper to make it readable. That’s what the lemon was for.

Hack a car to make it drive

Oh, this is sadly real. You know—we like to assume that we can add cool features to our cars and they will be safe. Apparently, this is not the case. Here’s a video showing a remote car hack.

I guess that 1985 Honda Civic looks like a pretty good choice now. Right?

Rocket fuel

Yes, you can get rocket fuel from liquid oxygen and kerosene – it’s called RP-1.

DIY Nitrous Oxide

Seriously—don’t do this. Here’s how to make it.

Stopping a torpedo

I know it’s a stretch—but’s also fun. There’s a torpedo traveling through the water system. MacGyver finds a “diaper factory”—I love that line and then he gets a bunch of sodium polyacrylate. It’s that stuff they put in diapers. When liquids get into this stuff, it gels up. So, putting it in the water will gel it up. The torpedo will hit the gel and slow down and stop. Save the day.

Actually, in a previous episode MacGyver used this stuff to make fake snow.

OK—one more thing. Why can’t MacGyver get out of the gel? Why is he in the gel? You will have to watch the episode to find out.

But here’s the deal. He’s stuck because of the atmosphere. Yes, there is a bunch of air above him pushing down. The air pressure is 10^5 Newtons per square meter. If you try to lift him up, air can’t get in below him so there’s just the atmosphere pushing down. You are going to either have to pull up REAL hard or get some air down into the gel.

Don’t worry, Mac survives. SPOILER ALERT.

Top 10 Blog Posts from 2019

It’s always difficult to pick the BEST of stuff. This is especially true when it’s all your own stuff.

So, let’s just say these are 10 nice posts from 2019.

How Does the Mandalorian See Through Walls?

You know I love to write about stuff that gets me excited—and I’m super pumped up about The Mandalorian (just finished season 1). In one of the episodes, Mando sees through a wall with his sniper rifle. How would that work?

side by side photographs showing boy holding up sheet

No, it probably wouldn’t be with infrared.

Modeling the Water from a Spinning Sprinkler

You don’t really understand something unless you can model it. In this post, I use python to model the motion of water shooting from an inward pointing and spinning sprinkler (based on the Steve Mould and Destin video).

This gif pretty much sums it up.

Orbital Physics and the Death Star II at Endor

This is my favorite thing to do (which I also did in the Mandalorian post above)—take some scene from a movie and and then use that as an excuse to talk about physics. In this case, it’s all about geostationary orbits from Star Wars: Return of the Jedi.

Bonus: more python code in this post. Double bonus, I use data from ROTJ to estimate the length of a day on the planet moon of Endor.

All Measurements Are Really Just Distance—or Voltage

I was in lab when I realized that pretty much all of our measurements were actually measuring distance. Well, originally that was true. Now we can make measurements by measuring a voltage.

Here are some measurement devices—this wasn’t in the original post.

You Can’t Calculate the Work Done by Friction

This was a post I wrote after a discussion I had with Bruce Sherwood. He told me this story about how it’s easy to use the momentum principle with a sliding block (with friction), but you can’t use the work-energy principle.

We like to think friction is this simple thing—but it’s not. The above image is an illustration to show that the distance a friction force is applied is not the same as the distance the object moves.

Video Analysis of Captain America vs. Thanos

There is the perfect scene in Avengers: Endgame. It’s not only perfect because of what Captain America does—but it’s perfect for video analysis. So, in case you haven’t seen it, Cap takes Thor’s hammer and smacks Thanos hard.

Here is the frame corrected version after using Tracker Video Analysis.

No, momentum is not conserved. But that’s OK.

What are Maxwell’s Equations?

Yes, Maxwell’s Equations can be tough.

an equation

Here is my attempt to explain these equations in a simple way to describe the electric and magnetic fields.

Every Jedi Jump in Star Wars

OK, not every Star Wars movie. I didn’t have Episode IX to include at this time (I will have to wait for the digital version of the video). But the idea is to analyze ALL the jumps. Here they are.

There are too many jumps for me to do a complete video analysis. Instead, I just estimated the jump height and the jump time. From these two values, I can make a graph—if the vertical acceleration is constant then there should be a linear fit.

The best part is that most Jedi have a vertical acceleration LOWER than g (free fall acceleration on Earth). Yoda has a vertical acceleration HIGHER than g because he takes so many short jumps. I need to write a future post just looking at Yoda.

All the Hacks and Science from MacGyver Season 3

Maybe this is cheating since it’s really not just one post. This is a list of all my science explanations for MacGyver Season 3. Oh, just to be clear—I’m the Technical Consultant for the CBS show MacGyver (season 4 starts in February).

It’s a lot of work to help the writers come up with new science tricks for MacGyver, but it’s also super fun. I also really enjoy making these MacGyver at home videos.

I’m really looking forward to sharing more science for season 4.

Projectile Motion in Polar Coordinates

I’ve had this secondary blog for over a year now—and I really like it. It’s like the old days of blogging. I can write whatever the heck I want (example—the top five lightsaber fights in Star Wars). Also, I can go into super complicated physics stuff.

Here is an example from my upper-level classical mechanics course. Can you use polar coordinates for projectile motion? Yes you can—but it’s obviously not the best choice.

newplot (3).png

There’s python here too.

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

I honestly don’t know how I skipped over this episode with my MacGyver science notes. Oh well, let’s finish this up. There aren’t too many hacks in this episode, so this won’t be too long.

One Way Mirror

Murdoc makes a great point. Is it a one way mirror or a two way mirror? The main idea is that Murdoc can’t see through the glass, but the other people can see through to view what Murdoc is doing.

These things aren’t magic. At the most basic level, a “one way mirror” is just a plane of glass. When light hits glass, some of it is reflected and some of it is transmitted. If you are on one side of the glass and there is WAY more reflected light coming back at you than the light transmitted from the other side, then you can’t see that transmitted light. The glass would look like a mirror.

This is exactly what happens when you are inside a house at night with the lights on. The lights reflect too much and there isn’t much light from outside coming in, so you just see a reflection. It would look like this.

If you are outside on a dark night, the opposite is true. You can see INTO the house.

So, for the one way mirror, you need a glass separating two rooms. The dark room is the room with the observers and the light room is where the prisoner sits.

Here is an older post with more details about seeing through windows.

Pulley Skateboard Battering Ram

This is a classic simple machine. The key to all simple machines is that you can make a system that pulls over a greater distance and produces a greater force (or you can do it the opposite of this).

In this case, MacGyver makes a compound pulley. You need two pulleys. If you run the string through these two pulleys, you can make two different distances. The distance one side is pulled is twice the distance of the other side. Here is a diagram.

Yes, that’s a rather crude sketch—I did it fairly quickly. Here is a video that walks through the setup. I mention that there are two ways to set up this skateboard battering ram, this only covers one method.

Here is a much more detailed post on pulleys.

Stopping a Truck with a Truck

MacGyver uses a winch cable to connect their truck to Murdoc’s truck. They then slam on the breaks. So, would this work? Yeah, probably.

Assuming the two vehicles have the same material for the tires, then they would have the same coefficient of friction. A basic model for friction says that the frictional force is proportional to the force the ground pushes up on the object (we call this the normal force).

F_f = \mu N

Since both cars are on flat ground, the normal force is equal to the car’s weight. That means the heavier car would have a greater frictional force. Yes, I’m making some other assumptions about the tires “locking up”—but still, this is plausible.

Even if the frictional force wasn’t enough to stop the truck, the cable is attached to the side of Murdoc’s truck. This side force would rotate the truck and also prevent it from driving straight.

MacGyver Season 3

Here is a list of all of my science notes for season 3

MacGyver Season 2

Here is a collection of all my science notes for Season 2.

Here is the list of notes for Season 1

MacGyver Season 2 Episode 23 Science Notes: MacGyver + MacGyver

It’s funny how the title is sort of a spoiler for the episode. Right?

DIY Safe Cracker

This is technically a MacGyver-hack since it’s from MacGyver, just not from Angus MacGyver.

The basic idea is to open a safe with a dial on it. Instead of trying to figure out the lock combination, a robot can just try EVERY combination. This is called a brute-force hack since it’s not elegant but it works.

Oh, you want to build one of these yourself? You are in luck, here is an epic guide.

Also, here is another brute force hack (on a key code door).

Book Cipher

I’ll be honest. I had no idea how a book cipher worked. But with a little help from the internet, I finally figured it out. Here’s how it works.

  • You take some text that you want to send. The example I use is the word “cat”—yes, that’s sort of silly.
  • Next, you need to convert each letter to a number. I’m using the ASCII UTF-8 format to convert each letter to a hexadecimal number (base-16 numbers instead of base 10). For “cat” this would be 43 41 54.
  • Now I take a word from my “book”—in this case it’s a take out menu from a Chinese restaurant. If I use SPR (from spring roll), I can also convert that to ASCII to get 53 50 52. This is my key.
  • Now I add my text and my code to get 96 91 A6. REMEMBER these are hex numbers, so you have to add them differently than you would with decimal numbers. This gives me the code—this is what you send.
  • To decode the message, you just do the opposite.

Here is a longer explanation with a video.

Just for fun, here are some of my notes along with Oversight’s calculations on the dashboard.

Fuel Pump

MacGyver needs to transfer fuel from one car to another. Here is a very cool pump.

The key to most of these pumps is a one way valve. You need to make something so that water can flow the way you want to pump, but not the other way. Here is a very simple way to make a one way pump valve with a turkey baster and small ball.

Belt Handcuffs and Bolo

Really not much to say here—normal MacGyver stuff.

Ascender Rig

MacGyver and MacGyver build a device so that they can get on the roof a building. Yes, it’s an ascender rig. It’s basically just a battery (a car battery in this case) and an electric motor. The motor winds up a rope and causes the whole thing to move up.

Here’s the cool part. You could really do this with just about any electric motor. Yes, even that tiny weak motor could still lift two humans. The only difference would be the speed. If you get the gear ratio right, this tiny motor would slowly wind up the rope and just take longer to get to the top.

Spark Gap Generator

The spark gap generator was the first type of radio transmitter. When a spark is created, it also produces electromagnetic waves (over a broad range of frequencies). That means you can’t really have radio channels, but you can indeed send a signal.

If you want to know more about spark gap generators, here is some info. I even built one mostly from scratch.

But could you make a spark gap generator with a magnetic stirrer? I think so. One of the key things you need is a changing electric current. If you use the spinning stirrer, it can make electrical contacts at different points during the spin. Here is an example.

MacGyver Season 2 Episode 22 Science Notes: UFO + Area 51

NASCAR Physics

Here is a great homework problem for you. What physics or technical advice could MacGyver offer to a professional NASCAR driver to improve the track time? It’s tough, right? I mean—you could say “go faster” or “get a bigger engine” or stuff like that. But haven’t they already thought of the “go faster” strategy? Probably.

How about this? What if there is a significant wind at the track? Let me start my explanation with a diagram. Note: I am just a physicist and not actually a NASCAR expert.

Inline image 2

I incorrectly labeled the turns as “A” and “B”, but let’s call turn B turn 3 instead (like in the show). So, suppose there is a wind coming from the North. That means that in turn 3, there will be more air resistance (going into the wind) than in turn 4 (going with the wind).

In order to decrease the time in turn, the driver could take the inside of the turn. This would mean that the total distance is shorter (because it’s a smaller circle for the inside turn). If you take the outside turn, the car can travel faster but over a longer (slightly) distance.

But with air resistance, you might be able to make a small improvement on time by driving the slower and shorter distance. Yes, it is indeed true that the normal model for the air resistance force is proportional to the square of the relative speed between the car and the air (but air resistance is in fact quite complicated).

Testing an Unknown Object

MacGyver and Riley meet up with a scientist that is trying to identify an unknown object. You might have missed it, but there is a nice list of tests on the board in the background.

I could probably write a whole book about these tests, but let me just point out that density is a great one to start with. The density is the ratio of mass to volume for an object, but it can tell you a lot. Is it hollow? Is it solid? If it’s solid, the density of a material is one way to identify the exact material. Plus it’s a super simple test that wouldn’t destroy the object.

Salt Water Faraday Cage

Yes, this is essentially a Faraday cage. MacGyver covers the sphere with a lab coat soaked in salt water. The salt produces ions that turns the water from an insulator into a conductor. Once you have a conductor around the sphere, then charges can move around to make an electric field that cancels the field in the radiated electromagnetic wave.

One thing about a Faraday cage like this—it doesn’t stop all electromagnetic waves. Since the electric field oscillates back and forth, the charges in the liquid can’t always adjust fast enough. This means that this could block some frequencies of electromagnetic waves—but not others.

Liquid Metal Isn’t Completely Crazy

What the heck is up with this metal that turns into a liquid? Yes, this is partly science fiction—but at least it’s based on some real stuff.

Here is a liquid metal that can form into a shape based on an electric current.

Moving a Wounded Scientist

It’s called a travois— The basic version is just a cloth stretched between two sticks. Then you put a person on the sticks and drag it.

For MacGyver’s version, he uses some wheels.

Celestial Navigation

Here is the line that I recommended:

“The idea of celestial navigation is pretty simple—it’s the precision that’s difficult.”

If you want to find out where you are on the Earth, you need to get your longitude and your latitude. Finding your latitude is really quite simple—especially in the Northern hemisphere. If you just measure the angle that the North Star lies above horizon and subtract from 90 degrees, that’s it.

This is essentially the role of a sextant. It’s just a really fancy way of measuring angles. They really aren’t too hard to build, here is one that I made.

What about longitude? That’s a much tougher problem. One way you can find your longitude is by measuring the time of local noon (the time that the Sun is at its highest point) and comparing that to the noon in Greenwich. So, that means you need a very nice clock. In fact, this was the biggest obstacle to overcome for early navigation, the invention of a reliable clock.

Of course MacGyver has a clock. However, he doesn’t have the Sun since it’s at night. One way to solve this problem is the observe the rising time of some known star (other than the Sun) and compare this to that star’s normal position in the sky. Knowing this time could give you your location, but you need to know the celestial coordinates of a star. MacGyver is enough of a nerd (in a good way) that he might have a particular star memorized.

In order to be over prepared for the show, I made a video going over the exact calculations MacGyver might make.

DIY Spot Welder

Yup. You really just need some high voltage and current and you can weld some stuff. Here is something similar to MacGyver’s build using the transformer from a microwave.

Welding Glasses

Don’t try this, but it should work. Those old floppy disks are partially transparent. If you take about the hard part of the disk, the spinning part (where the data is stored) is both easy to cut and could make some welding glasses.