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

Breaking Window Bars with a Bicycle

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

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

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

$W=Fd$

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

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

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

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

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

Here is my initial diagram for how this might work.

Spark Gap Generator

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

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

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

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

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

Here is a video.

Here are some more details on this.

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

Gum Wrapper Switch

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

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

Here is a diagram I created for this.

# MacGyver Season 1 Episode 18 Science Notes: Flashlight

Hold on. There’s a metric butt ton of science in this episode. It’s going to be great.

Turning bullet

SPOILER ALERT. This episode has a bullet that can turn. It’s sort of the key plot element in this episode. These dudes are trying to steal the technology for these “smart bullets”. These bullets are essentially tiny guided missiles with fins so that they can turn in flight.

I’ll just leave this Wikipedia link on smart bullets and then move on (it’s not really a MacGyver hack anyway).

The physics of birthdays

Again, not a hack—but MacGyver thinks birthdays are dumb. Well, not dumb but arbitrary. I think he is right. In fact, I use the following phrase on people’s birthday’s:

Happy Solar Orbit Day.

Yes, that is the day the person completes another orbit around the Sun. I like thinking of it that way.

Fixing a generator inverter

There are lots of different types of generators. Most of them involve a gasoline engine that turns stuff. Some times this turning stuff involves a magnet to make an electric current. But what happens when the magnet get’s messed up? Yes, you have to fix it.

A permanent magnet is a ferromagnetic object (like iron) in which all the magnetic domains are aligned. If the domains are not aligned then it would just act like a dumb piece of metal. You can get the domains align by applying a strong magnetic field.

This is exactly what MacGyver does to the generator. He uses a defibrillator to generate the current and forms a loop of wire to create the strong external magnetic field. Seems like it could work.

DIY sand blaster

How do you get people out of a collapsed building? What if you could just cut through the wall? Yes, that’s the MacGyver plan.

In this case, he uses high pressure water mixed with sand—a type of sand blaster. If you have water at a high enough pressure, it can pretty much cut through anything. Of course MacGyver’s water by itself isn’t fast enough. That’s where the sand comes in. When the sand hits the concrete, the abrasive interaction is enough to eat away at the concrete.

Oh, this would take quite a while to work.

Seeing through walls with radar

Yes, this is a real thing. NASA made this device. Here is a description. Basically, this thing sends out microwaves and detects the reflected microwaves. But the magic is that it only looks for variations in reflections caused by small oscillations—these oscillations are from a human heart.

For MacGyver’s version, he starts with a radar gun (from a police car). These don’t use the same frequency as the microwave detector, but he can make a modification. With some software from Riley, that’s pretty much what he needs to get started. It’s at least plausible.

Screw jack

How do you lift super heavy stuff? You need a simple machine. All of the simple machines deal with force and distance. If you can increase the distance over which you apply a force, you can get a greater output force over a shorter distance.

In this case, MacGyver makes a screw jack. You can lift a large mass by turning the screw to get it to extend. In fact, you could do something like this yourself. Here’s how.

Ascender rig

The goal of an ascender rig is to allow some device to move UP a rope, but not down. This means you can climb up a rope one little bit at a time. Here is an example.

Oh, MacGyver made an ascender rig to climb an elevator cable and escape a collapsed building.

Modify laser

The smart bullet is aimed using a laser. Of course the bullet is only a little bit smart. It only aims towards the brightest laser. If you could make another laser that gets the attention of the bullet, you can get the bullet off course.

MacGyver takes the laser sight off a pistol. In order to increase the power output, he burns off a potentiometer. This could work on some lasers—like this.

Oh, DON’T DO THIS. You don’t want a powerful laser without knowing what it can do. These lasers can seriously damage your eyes in ways you wouldn’t be able to predict. Remember, you only have two eyes. Don’t mess them up.

So, they use this powerful laser to redirect a smart bullet. That part is plausible. It’s unlikely they could get a bullet to turn all the way around. They wouldn’t have time to move the laser dot and the bullet fins couldn’t make it turn that much.

Who cares. It was still a great episode.