Analysis of a borked lab

It happens all the time. It even happens to you. There is a new lab you want to try out—or maybe you are just modifying a previous physics lab. You are trying to make things better. But when the class meets—things fall apart (sometimes literally).

Yes. This is what happened to me this week. And yes—it’s OK.

But let’s look at the lab and go over the problems so that I can make it even better for the future.

Finding the electric field due to a point charge

This is a lab for the algebra-based physics course. It’s always tough because many of the first things they cover in the lecture class don’t have lab activities with things you can measure. Oh sure—there is that electrically charged clear tape lab, but it will be a while before they get to circuits.

So, my idea was to have the students use python to calculate the electric field due to a point charge. This would give them a safe and friendly introduction to python so that we could use it later to get the electric field due to other things (line a dipole or a line charge). It would be great.

Here is the basic structure of the lab (based on this trinket.io stuff that I wrote – https://rhettallain_gmail_com.trinket.io/intro-to-electric-and-magnetic-fields#/introduction/vector-review

You can look at that stuff, but basically I give a workshop style presentation and have the students do the following:

  • Review vectors. Add two vectors on paper (not with python).
  • Find the displacement vector – given the vector for a point, find the vector from that point to another point (the vector r).
  • Find the unit vector and the magnitude of a vector (using python).
  • Next, find the electric field due to a point charge for the simple case with a charge at the origin and the observation point on the x-axis. Do this on paper.
  • Now do the same calculation with python.
  • Find the electric field at some location due to a charge not at the origin (in python).
  • Use python (or whatever) to make a graph of the electric field as a function of distance for a point charge. Graph paper is fine. If they wanted to, they could do the calculations by hand (or use python).
  • Finally, give a quick overview of the sphere() and arrow() object in glowscript.

So, that was the plan.

Lab problems

Here are the problems students had during this lab.

  • Computer problems. Yes—whenever using computers, someone is going to have a problem. In this case, it was partly my fault. There was one computer that was broken and some other ones weren’t updated. Honestly, the best option is for students to bring their own.
  • I can see that there are some students that just sort of “shut down” when they see computer code. They automatically assume it’s too complicated to grok.
  • Students working in big groups. I hate having 4 students use one computer. That’s just lame.
  • Too much lecture. The first time I did this, I spent too much time going over vectors with not enough breaks for students to practice. I partially fixed this for the second section of lab.
  • Some students were just lost on vectors.
  • Yes, the unit vector is a tough concept.
  • I’ve learned this before—but I guess I need to relearn. The visualization (sphere and arrow) are just too much for many students. That’s why I moved it to the end in my second section.

So, that’s it. I am going to rewrite the lab stuff on trinket.io. I am also going to change my material for the dipole stuff that they are doing next week. Hopefully it goes well. Let’s just see.

MacGyver Season 1 Episode 13 Science Notes: Large Blade

Tarp restraint

This is sort of like a straight jacket made out of a tarp and a belt. I wonder how long this would last—but it’s still a classic MacGyver hack. This blog would probably be better if I included pictures. Oh well.

Space blanket as chaff

A space blanket is basically a thin mylar sheet. It has a nice property in that it reflects infrared radiation. The idea is that you cover yourself with this and when your body radiates infrared light, it reflects it back to your body.

Can you use this as a countermeasure against a ground to air missile? Maybe. Of course there are two types of missiles. There is the heat seeking missile and the radar missile. For the heat seeking missile, it is guiding by the giant infrared source—the engine of the aircraft. It’s a least plausible that this space blanket could block the infrared light from the helicopter enough to confuse the missile. Possible.

If the missile is radar guided, then you can block the radar that comes out of the missile. This is the idea behind chaff (a real thing). It’s basically thin strips of metal that fall in the air behind an aircraft. The metal spreads out and can make a large radar reflection such that the missile thinks it’s a target.

Would a space blanket work? It’s possible. Really, you want metal—but this might work at least a little bit.

Splint and crutch from helicopter parts

Classic MacGyver stuff here. Nothing else to say.

Clean water from a tree

Can you get clean water from a tree? It seems like this is legitimate.

Dried wood as a desiccator 

This seems like a plausible way to dry out a wet phone. It would take some time though.

Swiss Army Knife as a signal mirror

MacGyver uses the blade on his knife to attempt to reflect sunlight towards a rescue helicopter. I’m pretty sure this would work.

As a side note—I’ve been thinking about the brightness of light reflected from a mirror (for another project). It seems like this is fairly difficult to calculate. Perhaps the best way is to just experimentally measure the brightness of reflected light. I guess I will do that at some point.

Tree sap and a battery to start a fire

If you want to use a battery to start a fire, you need an electrical conductor. This allows electric current to flow from one terminal of the battery to the other. It’s this electrical current that can make things get hot—hot enough to catch on fire.

So, the battery part is good. What about the tree sap? Yes—apparently, it is indeed a conductor. There you go, a fire.

Distance to lightning strikes

This is another reminder. I should write a post about how to estimate the distance to a storm. The short answer is that when lightning strikes it produces both light and sound. The light has a super high speed, but the sound is just fast (not super high fast). This means that the light gets to the observer first. By counting the time between the “flash” and the “boom” you can estimate the distance.

I thought I had already blogged about this—but I can’t find any such post.

Creating a homemade capacitor to store charge

Here is the short version: MacGyver makes a DIY electrical capacitor (a Leyden jar) to get some electrical charge from a lightning storm. He then uses this to power the satellite phone.

The Leyden jar is totally real. Honestly, I was surprised at how well this worked. Check it out.

Photo Google Photos

Also, I have a much longer blog post over at WIRED.

Finally, you can make something like this yourself.

Zipper as an wire

MacGyver uses the zipper to make a complete circuit from the battery to the sat phone. Would this work? It’s tough to say. In order to get an electric current, you need a closed circuit with a conductor the around the whole path.

Parts of a zipper are clearly conductors (the metal parts). However, if there are gaps between the metal, then it wouldn’t work. If you zip the zipper, there should be contact—at the very least, this is plausible.

MacGyver Season 1 Episode 12 Science Notes: Scissors

Stove Bomb

MacGyver needs a distraction to escape from a cabin in the woods (surrounded by bad guys). He puts some chemicals into an iron stove and rolls it out the door.

The stove explodes when someone shoots inside of it—it’s not because of the spark from a bullet (because they don’t really do that). No, the bullet has to puncture the can of stuff in there to mix the chemicals. That’s what causes the explosion.

Also, a quick note—that stump remover is some bad stuff.

Cheese puffs to get past phone lock screen

How do you find someone’s pin code? MacGyver crushes up some cheese puffs and sprinkles them on a phone screen. The oil from someone’s fingers leave some residue that makes the cheese puff crumbs stick to the phone.

Now you know which numbers are used in the pin code—you still have to figure out the order (and this case it was three numbers so there was one used twice). But MacGyver figures that it’s an important number.

MacGyver Season 1 Episode 11 Science Notes: Scissors

Kill computer stuff with a transformer

How do you get a hacker to do what you want (or tell you want you want)? You start destroying all his electronic stuff. In this case MacGyver uses a transformer to zap some computer equipment.

What is a transformer? It’s basically a coil of wire connected to an AC voltage (like your wall outlet). This AC outlet makes an alternating current in the coil that produces an alternating magnetic field.

Now for the second part of the transformer—another coil. Yes. If you have another coil of wire, the changing magnetic field from the first coil will induce and electric voltage in the second coil. By changing the number of turns in the two coils, you can either increase or decrease the original voltage—or perhaps you could say you “transform” the voltage. Get it?

OK, so MacGyver takes this transformer. With it, he creates a high voltage. The voltage is high enough to make a spark—this is indeed possible.

Next question: how does this spark kill a computer? Well, it’s not the spark but rather the electric current. If you get extra electric current going through the computer stuff, you can destroy those super tiny transistors. They weren’t meant to have much current. Without the transistors, you are pretty much a plain electric toaster.

Scissor Extenders 

MacGyver needs to cut through a cable. It just so happens that this cable is choking someone—so he needs to move quickly. Of course he has scissors on his Swiss Army Knife, but he can’t push hard enough to cut the cable.

This is where the scissor extender comes in. MacGyver gets a long stick and adds it onto the end of the scissor handle. With this long handle, the same pushing force can create a much larger torque on the scissors (torque is the product of force and lever arm). This larger torque is enough to cut through the cable. It’s just like those super long handle sheers that you can use to trim tree branches or those bolt cutters that you can use to cut a chain.

OK, there is one small problem here. One stick might not be that helpful. If you have one long handle and one short handle, then you would have to apply the same torque on the short handle. That would be pretty tough.

Hack a car

This isn’t a “Mac Hack” —but I am going to talk about it anyway. There is a program that can hack into cars and take them over. Sadly, this is partially true. Check out this video from WIRED in which some hackers remotely stop a Jeep. Scary.

Could this be used to take over a nuclear submarine? Well, probably not.

Air Raid Siren

This is classic MacGyver. He creates an air raid siren out of PVC pipe and an AC condenser fan. It would probably work.

I was going to build one of these and make a video, but I didn’t. Here, check this one out instead.

RFID range extender

So, the guys want to use an RFID badge to access a security level in an elevator. MacGyver builds a DIY range extender. This is fairly plausible, but I won’t go over all the details. Instead, I will just share this paper.

Faraday cage

The whole building is a Faraday cage. The basic idea is to create a grounded metal enclosure so that electromagnetic waves can’t penetrate. That means, no phone signals and no wifi outside of the building.

Here is an example of a Faraday cage (from a later episode, but who cares—right?).

Spoof GPS

There is a missile flying towards the USA. That’s bad. MacGyver builds a parabolic dish to act as a GPS spoofer. This could basically work. The signal from the dish could be stronger than the one from orbit and trick the missile into going the wrong way.

Of course, there is one small problem. If the missile is 3000 miles away, you couldn’t get direct-line sight of it unless it was super high. Well, I guess these missiles do go pretty high. Still, it would be hard to aim it.

It’s still plausible.

Artificial snow

How do you make fake snow? One way is to shoot water out of a nozzle at high pressure. When the water leaves the nozzle, it expands and cools off. If it cools off enough, it will freeze and make something that is like snow. These things are real.

But can you make snow above the freezing point? Oh yeah.

MacGyver Season 1 Episode 10 Science Notes: Pliers

Boosting car speed.

Mac and Jack are trying to get away in a car chase (using a not very fast car). Of course MacGyver is going to give them a speed boost, but the first step is to remove the car hood. MacGyver makes some small explosives using chemicals and soda cans. Boom. No more hood.

The second step is to remove the air filter and pour some hydrogen peroxide into the intake. What would this do? This would give the gasoline more oxygen (from the hydrogen peroxide) to produce more combustion. Would this give a speed boost? Probably—at least a little bit.

Chemistry demo – elephant toothpaste.

This is real. Everyone does this—at least all the cool kids do it. You should be cool.

Liquid nitrogen in water

OK, liquid nitrogen is pretty awesome. It’s the same nitrogen that you find in the air, but in liquid form. That makes it very very cold (-196 C). When you add it to room temperature water, the liquid nitrogen boils. In this boiling process it produces a bunch of water vapor—stuff that looks like a cloud.

This was for a different episode, but here is my introduction to liquid nitrogen.

Remote listening device

MacGyver wants to hear what is going on inside a house. The obvious solution is to build a remote listening device. Here’s how it works.

A laser is aimed at a window such that the laser reflects off the window and back to a solar cell. Because people are inside the house speaking, this causes tiny vibrations in the window. The window vibrations vary the intensity of the reflected laser light. When this reflected laser light hits the solar cell, it causes variations in the voltage. Plugging this solar cell into an amplified speaker produces sound. Yes. This is real.

It’s pretty awesome—and you can do something like this yourself. All you need is an amplified speaker and a solar cell (don’t worry about the laser). Connect the solar cell to the audio input and you can hear variations in different light sources.

My favorite trick is to aim a TV remote at the solar cell. You can hear the variations in the IR light that produce different signals to change channels.

Here is a video.

Stop a car with paper

Yup, a version of the banana up the tail pipe from Beverly Hills Cop (great movie). See—everyone is a version of MacGyver at some point.

In this case, MacGyver sticks some paper up the tail pipe of a car. When the exhaust can’t escape, you can’t get internal combustion. Car stops.

Yaghi Antenna

Yes, you can build an antenna out of just about anything—including band instruments. It helps if they conduct electricity. I think this would work.

Technically it’s possible to find the location of a signal with just one antenna (well at least the direction). Just turn the antenna until you get the maximum signal. A better option is to use 2 or more antennas—but you have to work with what you have.

Over inflate tire

Yup. Boom.

Elephant toothpaste version 2

Bigger is better, right? It’s sort of funny.

MythBusters Jr. Slinky Drop Stuff

Tonight’s episode (actually there are two episodes tonight) looks at the famous slinky drop problem. Let’s start with the first place I saw this—from Derek Muller (Veritasium) even though he didn’t invent this either.

That’s pretty awesome, right? Of course the first thing I want to do is to make a model of a falling slinky. Here is that first post.

Some important comments.

  • It’s important that the slinky itself has mass. You can’t use the normal assumption of a massless spring.
  • The best way to model a spring with mass is to have a bunch of smaller masses connected by massless springs.
  • When the slinky is dropped, the center of mass falls with a downward acceleration of -9.8 m/s^2.
  • However, since the slinky is contracting this makes the bottom of the slinky motionless.
Untitled 2

Here is an animation of my python model.

Slinky 3

Sorry—this code is older and I don’t have it on some online platform (I will try to update that soon). But here is the important plot. What if you look at the vertical position of the top, bottom and center of mass for this “slinky”? Here’s what that looks like.

Slinkydrop 2.png

The red curve is the bottom mass. Notice how it “hangs” there? Awesome.

But can you just put a mass (like a car) on the end of a spring and drop it? Yes, but it won’t look very cool. The key is the center of mass. You want the center of mass to fall such that the bottom mass stays in place. With a car and a spring, there is no top mass moving down faster than the acceleration due to gravity to make the bottom mass (the car) move up relative to the center of mass.

In the end, you need some type of mass at the top of the spring too. So, that could work. Two large masses separated by a spring. When you hang and then drop, the bottom mass will be stationary.

But wait! You can try this yourself. Get two masses and connect them with rubber bands (even though rubber bands aren’t ideal springs). Hold one mass and let the other hang below. Now drop.

Here’s what that looks like in slow motion. Sorry about the vertical video, when I recorded this I didn’t think I would post it.

Pretty awesome.

But wait! What if you want to make something like the slinky? In that case you can get a bunch of masses and connect them with rubber bands. It will be just like the python animation above, but in real life.

I should have recorded this in slow motion. Oh well.

Just for fun, here are some of my original notes in which I estimate what kind of spring you would need to do this drop thing with two cars.

MacGyver Season 3 Episode 13 Science Notes: Wilderness + Training + Survival

There is no funny intro for this post. Oh wait, this is an intro.

Rock and steel to make a spark.

OK, this isn’t actually a MacGyver hack in this episode but I’ve talked about it before. Here is a video.

Other fire stuff

Are there certain plants that ignite more readily than others? Yes. Here is a nice article from Field and Stream that goes over the basics.

What about burning poison oak? Yes, that is bad too.

Wet cotton clothes are bad

Again, not a hack—but cotton is terrible when wet (so is denim jeans). When wet stuff is next to your body, the water evaporates. In this process the liquid water turns into a gas water (water vapor). The phase transition requires energy. Guess where the energy comes from? Yup, it comes from the human. This makes the human colder. Here is my more detailed explanation.

What about wool and other materials? The key to these better fabrics is that they “wick”—they pull the water away from the body. Here is a nice post on that.

Zipper for ice traction

MacGyver takes the tent zippers and uses them on people’s shoes for added traction on ice. It’s sort of like mini-spikes on your shoes. Classic.

How to make drinkable water

MacGyver uses a tree branch to act as a water filter. This seems to be real (from MIT) so you know it’s got to be good.

Here is a nice video showing how this would work.

Making rope (string)

I’ll admit it—I’ve never really understood how this works. If you take some vine or some other material, it has a certain maximum strength in its tension before it breaks. If you take two of these things together, it doubles the strength. If you take these two things and then twist them—the strength is more than double. What? But it does indeed work (I need to do an experiment sometime to really understand this).

Here is an older video in which I attempted to make rope from a TV guide.

Size and weight of 18 million dollars

This is a classic MacGyver estimation problem. How do you find the size and weight of a bunch of money? Why does it even matter? Well, one big thing is to find the density of the money. If the density is less than the density of water, then the crate of money would float and then be swept away in a flash flood.

Yes, you don’t need the weight and size—but just the density. However, if you want to estimate how long the crate was floating you DO need the size. Bigger crates will “hit the bottom” before smaller crates.

If you want to look at more stuff about the density of money, here is an older post in which I find out how far 1 trillion dollars would stack. Would it make it to the moon?

Surveying tools

How do you find the slope of the ground? This is where you need surveying tools. Here’s how it works. Get a scope (from a rifle) and make sure it’s aimed level. There are plenty of ways to level a scope—those little bubble levels work great. Next get a survey stick. Make sure this is also vertical and then measure where the scope points at the stick.

If you know the change in elevation and the distance between the stick and the scope you have the slope.

Float distance calculation

Yeah, this is pretty tough—but that should never stop anyone from trying. How do you estimate the distance a crate will float in a flood? Here are some things to consider (some of these would be tough to estimate).

  • How fast was the water flowing?
  • How deep did the water get?
  • How long did the flood last?

Really, if you know those things you can calculate the speed and time of the floating crate. This would then give you the distance. From that you can find the location on a map.

Drag sled

To move a crate (or an injured MacGyver), it shouldn’t be too hard to make a drag thing—called a travios.

Grab hot coals

Don’t try this at home, but it is indeed possible to grab hot coals. Essentially, you can grab hot stuff if you are really quick. There isn’t enough time to transfer energy to cause a major burn.

It’s just like walking on hot coals. Here is a nice physics post on that.

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

Toothpick in grenade

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

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

What is a dirty bomb?

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

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

Electromagnet

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

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

Wall walk

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

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

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

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

Here is a better option.

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

Mercury Switch

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

Smartphone Radiation Detector

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

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

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

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

Rolling Tire Bomb

Yeah, mixing stuff and make explosions. The end.

MacGyver Season 3 Episode 11 Science Notes: Mac + Fallout + Jack

How do you break out of iron shackles?

So, Jack and MacGyver are stuck in a fallout shelter and they need to get out of shackles. Maybe they are just old iron or maybe they are old steel—either way, they need to get out.

There are several steel-busting options, but let’s go with something thermal. In this case he could do something similar to thermite (similar). How about glycerol and potassium permanganate?

Again, this is not thermite—this is the stuff that’s usually used to start a thermite reaction though.

Opening a door with thermal expansion.

MacGyver uses some butter knives and electric current to heat up a steel door. When the door expands it cracks the cement around it so that they can open the door.

Would knives heat up? Yes. When you short out an electric circuit, you get a bunch of current. Lot’s of electric current means that things get hot. This could theoretically heat up the door.

Now, if you are going to escape with this technique yourself you need to be careful. A steel door has a very large thermal mass. It would take some time to heat it up—but it would indeed heat up.

Do things expand when heated? Absolutely. Here, I made a quick demo for you.

Scuba shooting crossbow.

Yup. Basically this just takes some springs to store energy and then uses that energy to propel an empty scuba tank to break a door.

Zip gun

Jack has a small projectile in a tube with a spring—a zip gun. It’s basically a deadly sized nerf gun.

MacGyver Season 1 Episode 9 Science Notes: Chisel

There is no introduction, just science.

Lighter and spray can stun thing

MacGyver gets a broken spray can of something (it really could be any aerosol can) and attaches a cigarette lighter to it. He then makes it so the lighter burns while the spray sprays. When he throws it, boom.

Yeah, these spray cans can ignite stuff. This is plausible.

DIY hot air balloon for Jack’s phone

Someone needs to make a super clip of all the times Mac says “Jack, I need your phone”. I think that’s funny.

In this case, the idea is to build a mini hot air balloon to lift up the phone so that they can see a “bird’s eye view” of the city. Here’s how it works.

  • Get a thin plastic trash bag.
  • Get some fuel—in this case it’s that stuff that burns to keep food hot for a buffet or something. Oh, they put it in aluminum foil.
  • Hang the phone and light the fuel.

Boom. That’s it. Yes, it’s real. The basic idea is that the fuel heats up air that fills the bag. Hot air has a lower density than cold air—this means that the weight of the air inside the bag is less than the weight of air outside of the bag. This gives a net upward buoyancy force on the bag.

Here is a more detailed explanation of buoyancy, if you need it.

OK, but would this be enough to lift a phone? It would be tough, but it’s at least plausible. It depends on the weight of the phone and fuel, the size of the bag, the temperature of the inside and outside air. So, it’s possible.

Here is one you can make yourself.

Bullet proof paper

OK, it’s not bullet proof paper. It’s a calculation of how much paper you would need to stop a bullet. I love how well this turned out.

mythbusters bullet phonebook

Bullet proof shield

This one is simple. Yes, if you tape a bunch of kevlar vests to a door it will be fairly bulletproof. MacGyver’s calculation is great (I should know). OK, it’s not perfect—but it’s a good example how to make a basic estimation.

Personally, the dialogue gets to the basic point and the animations and graphics are really nice. LOVE IT.

Let’s go over some of the details.

  • You need some basic values—like the speed and mass of a bullet from an AK-47. I googled this, but maybe MacGyver just knew it.
  • From there, you want to somehow model the interaction between a bullet and paper. The first idea is to think of it like a drag force (just like a bullet going through air or something). Of course this causes a problem because that makes it a velocity dependent force and therefore VERY difficult to deal with.
  • But what if there is a constant force on the bullet during the interaction with the paper? In that case, we can use the work-energy principle (which MacGyver says—YAY!).
  • With a constant drag force, you can then find the distance over which this force needs to do work to stop the bullet.
  • For the constant drag force, I estimated the density of paper (a little bit lower than the density of water) and assumed this was the constant force. Of course this is wrong—but it’s just a place to start. You have to start somewhere.
  • Really, the rest is just calculations.

Here is my original estimation.

Oh, I guess there are a few things to point out. First, the MythBusters also looked at using paper to bulletproof a car. It sort of worked. Second, in the end MacGyver reports the paper thickness in inches. I hate imperial units—but I guess that’s just the way things are.

Still, super pumped at the way this turned out.

Improvised weapons

In order to fend off the attackers, MacGyver makes some improvised explosives to shoot marble cannon balls. I don’t want to go into the chemistry of explosives so I will just put my normal explanation.

Any time you mix two or more chemicals, it is plausible that it could make an explosion. The end.

Intercept radio transmission

MacGyver wants to figure out what the bad guys are saying on their radios. He uses a yaghi antenna to get a directional signal and then he connects it to an AM/FM radio and picks up the signal.

OK, they probably don’t broadcast on the AM-FM frequency range. However, it’s possible he could modify the tuner in the radio to pick up their frequency. It would help if he knew their frequency. Also it’s hopeful that they aren’t using encrypted radios.

Dish soap to slide a safe

This is basic physics. Dish soap can indeed decrease the frictional force—especially for smooth surfaces. This would make a great physics problem.

Sugar putty bomb

Again with the bomb thing—using sugar for an explosive. Well, you can make a rocket from sugar (again—from the MythBusters)

Radio detonator 

In order to detonate the explosives, MacGyver takes apart one radio such that it makes a spark when receiving a signal (instead of making a noise). This is fairly plausible.

There are a couple of other things, but I will stop here.