Honest commentary. I figured this would just be a “filler” episode with just a little side action. NO. This episode was great. Now for some science.
Bra Wire—Nickel Titanium
MacGyver uses Desi’s bra underwire to short out a fuse box. That’s cool and everything, but what’s really great is the nickel titanium wire—also known as memory wire. Here, check this out.
Yes, some bra’s have this kind of wire (also called nitinol) for the underwire.
MacGyver needs to find out what’s going on in another room by looking through an air vent. He uses a bathroom rail to mount two mirrors (oh, with gum as glue) to build a periscope.
Here’s how to build one yourself.
Lithium Battery Fire Bomb
OK, it’s not really a bomb it just starts a fire. MacGyver needs a distraction. So, he punctures a lithium-ion battery and then covers it with chocolate. When the chocolate melts, the battery is exposed to air. This is where the bad stuff happens. Don’t puncture your phone battery. Check this out.
Ping Pong Ball Flash Bang
It’s a ping pong ball with butane (from a lighter)—it would probably go boom. Don’t do this.
On top of that, when you get really small particles of stuff the surface area to volume ratio is huge. That means that there is a lot of the material that can interact with oxygen in the air—this makes it burn.
I love this one. MacGyver needs to lift a glass window out of the frame. He uses some glass jars with soap to make a nice air-tight seal. After that, he gets a fire inside of the jar (after it’s up against the window). This fire produces a suction so that he can lift the window.
This is indeed possible (at least plausible). Here, check it out.
Now for some comments:
Burning stuff is complicated. Yes, it uses oxygen (O<sub>2</sub>) and creates carbon dioxide (CO<sub>2</sub>). You might think that you don’t lose any gas—but you do. The amount of carbon dioxide is less than the initial oxygen.
Since there is less gas after the fire, the pressure inside of the jar is LESS than atmospheric pressure.
This lower inside pressure means the atmosphere pushes the jar onto the glass. This is what causes “suction”.
The jar would work really well if you lifted a glass straight up. With the jar on the side of the glass it would be more difficult. You would need a large frictional force between the jar and the glass—but it’s at least plausible.
DIY Electric Arc Lighter
The basic idea is to create a homemade arc lighter and use that to destroy the electronic computers in some cars and disable them. I’ve always wanted to build an arc lighter, here’s a nice video.
The basic idea is to create a very high voltage between the two terminals. If the voltage gets high enough, you can create a large spark between them. This spark is hot enough to light a fire or destroy a computer.
Resonance Wall Destroyer
How do you get through a wall with a speaker? Well, if you could have that speaker oscillate at a very particular frequency, it’s possible (but not very likely) that you could set up a resonance.
Here’s an example. Go out to the park and push someone on a swing. The person on the swing will go back and forth with some frequency. Let’s make it easy and say that they complete one oscillation per second (frequency of 1 Hz). Now, how do you make this swing go higher and higher? The answer is to also push with a frequency of 1 Hz. If you pushed every half second, sometimes your pushes would make the swing go higher but sometimes it would be pushing at the wrong time and decrease the amplitude. This is resonance.
Of course, the most famous example of resonance is when someone breaks a wine glass with only a voice—or at least just with sound. If you tap a wine glass (a nice one with thin walls), it will produce a tone at some frequency. Now play an external sound with this same frequency and you can break the glass. It’s awesome (I need to make one of these videos).
Here’s a nice resonance demo.
OK, back to the wall. Could this work? The biggest problem is the frequency. A wall doesn’t have just ONE frequency that it oscillates with—because it’s made of many different parts. If you thump a wall, it doesn’t make a nice tone.
Still, you could claim that this is plausible. Maybe some part of the interior of the wall DOES resonate. That could be enough. Oh, also you could make this a bit better. If you put a microphone on the wall to measure the resonance frequency, then you would know what tone to play.
Knock out grenade
This one’s tough—but again based on something real. Let’s just focus on the water part. When you increase the temperature of water, it does produce water vapor (water as a gas). If inside a closed container, this water vapor would increase the pressure. For a plastic water bottle, this increased pressure could put it at a tipping point. Just a little nudge in pressure and BOOM. It explodes. Don’t try that at home though.
This is basically the same thing as an automatic baseball pitcher—except for the homemade water bottle grenades instead of balls.
It consists of two wheels—at least one of them is powered. In this case, you could use the starter motor from the car to turn one of the wheels. When you put a bottle in between the rotating tires, the frictional force from the tire increase its speed until it goes flying.
It’s not a science comment, but I have to say this: a show is only as good as the villain. In this episode we see James Callis playing The Merchant. Bam. That was pretty good. I like it. I’ll be honest, I didn’t know who was playing the role of The Merchant before the episode. Of course, you might know James Callis from his excellent role as Dr. Gaius Baltar the show Battlestar Galactica.
Now for some science.
MacGyver is looking for a way to figure out who is losing soccer games on purpose. You can see the clip right here.
The key to any sports analytics is data. The more data you have, the easier it is to see trends and patterns. Of course, you are still dealing with humans—so they don’t always do exactly what you expect. But really, this is true for most forms of real world data.
If sports stats is your thing, you absolutely need to check out FiveThirtyEight.
How do you hear people that are far away? What about a directional microphone? MacGyver quickly builds one from a trashcan lid—this is plausible.
Sound is a wave (in the air) and waves reflect when they encounter a boundary (like a trashcan). If the trashcan lid is parabolic, these sound waves from a distant source will reflect in a way that they all meet at the same point. Like this.
Actually, this is a diagram of a parabolic mirror (from a blog post about mirrors) —but the idea works for sound also. You would just replace the red dot above with a microphone.
These things are real. They use something similar in NFL games so that you can hear the collisions between football players on TV. Oh, there’s also this great sculpture on the campus of NC State University. It’s basically two parabolic dishes made of concrete some distance away. You get a person to sit in front of each of the dishes and they can hear each other talk. It’s really cool.
Anyway, this is one of those hacks that I want to try out for real. Maybe soon.
Here’s the one that MacGyver made.
He probably should have had the microphone facing the other way (pointing into the trashcan lid)—but maybe he was in a hurry. He WAS in a hurry.
Nice. I could explain the basic idea behind card counting, but this video is better.
Magnet and a Roulette Wheel
How do you opposite cheat at the roulette wheel? What is “opposite cheat”? That’s when you do something to the motion of the wheel to make it so you lose. I guess this is still cheating though.
In this case, MacGyver uses a magnet to effect the outcome of the wheel. He grabs a magnet from a purse latch (fortunately, these are pretty common) and holds it over the wheel. Although magnets only attract ferromagnetic materials (iron and most steel and some other stuff), you can get a magnet to interact with any material that is an electrical conductor.
If you have a CHANGING magnetic field, this will create an electric field—this is just the way electric and magnetic fields work. Then, an electric field in an electric conductor creates an electric current. Here, you can see what happens when a magnet is moved into a coil of wire.
Finally, an electric current creates another magnetic field. So, this changing magnetic field makes another magnetic field to interact with the magnet. I know that seems crazy, but it’s true. All of it. Oh, we call these induced electric currents—eddy currents.
For MacGyver, this small magnet creates an eddy current in the wheel such that there is a tiny interaction to slow it down—and cause Desi to lose.
Seeing through skin with infrared
Yup. Again, this one is real. Apparently human skin is partially transparent to near infrared light. This is the wavelength of light just longer than red light (that’s why it’s near infrared). It’s the same stuff that’s used on IR remotes (compared to far infrared that’s used in thermal cameras).
So, if you shine an infrared light on the skin and look at it with an infrared detector, you can see through the skin. At least that’s the idea. Your puny human eyes can’t detect near infrared light, but most digital cameras CAN detect this. In fact, most cameras include an infrared filter so that you WON’T see the infrared light (many cheaper cameras don’t even have this).
If you have a camera without the IR filter, you can even see if your TV remote is working.
You can build a cell phone (or radio jammer)—it’s not too hard. However, it’s also questionably legal. I’ll just tell you the basic idea.
Suppose you wanted to make a sound jammer. You could do this by playing a REALLY loud sound. Then no one could hear anyone else talking. That’s essentially how the jammer works—but it’s with electromagnetic radiation instead of sound.
Don’t try this—it’s a bad idea. MacGyver grabs some type of light weight sign and uses it as a glider to get down on the field. Oh, sure—it might make you crash, but it’s at least plausible.
It’s not flying—it’s falling with style. But seriously, pretty much anything could work here. This would really work especially if there was any type of updraft.
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.
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:
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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:
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 (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?
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.
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?
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 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.
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.
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.
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.
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.
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.
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.
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).
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.