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Photo: Rhett Allain. Two views of a ball tossed in an accelerating elevator.

There is this great elevator in the Hyatt Regency hotel in New Orleans. First, it’s a fairly high acceleration elevator (some of them are just super weak). Second, it’s got a nice glass window on the side. This means you can see outside as you move up floor. But it also means that people can see outside INTO the elevator.

So, here is the fun physics question:

“What happens when you toss a ball up inside an accelerating elevator?”

I actually have a video of this situation. Check it out.

If you like, you can use video analysis to…


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Photo: Rhett Allain

If you are teaching or using physics, please DO NOT use this definition for the velocity in one dimension (it’s a bad idea):

“Velocity = distance divided by time.”

OK, technically there are some cases where this would be fine — but it leads to the really terrible version of velocity that looks like this:


DYI Cutting Torch

We start off with Desi inside some type of chamber. The air pressure is decreasing — that means that the density of air is getting to the point that there’s not enough oxygen to keep Desi alive.

MacGyver runs off to grab some supplies. He comes back with some jumper cables and a car battery.

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Image: CBS/MacGyver

The key here is the two carbon rods to connect to the jumper cables. He pulls these out of zinc-carbon batteries (the same one’s I used in this arc-lamp).

This is basically an arc lamp, but he uses the arc to…


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Image: NASA/JPL-Caltech

In case you haven’t noticed, the NASA Perseverance rover landed on Mars. Yeah, it’s kind of a big deal. But there’s something special about this rover — it brings with it a flying autonomous vehicle. Yes, it’s got a drone…on Mars. It even has a name. It’s called Ingenuity.

OK, so there was a bunch of research and development that went into designing and building a drone (you can call it a helicopter if that makes you happy) that can not only survive a rocket launch. …


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In introductory physics textbooks often have some version of the following two problems.

  • Here are two electric charges. Where is the electric field equal to zero (technically the zero vector)?
  • Here are two electric charges. Where is the electric potential (with respect to infinity) equal to zero?

Yes, the electric field is a vector and the electric potential is a scalar — so you would think that the question about potential might be simpler, but not so. If you only have two electric charges, the electric field vector can only be zero on an axis connecting the two charges.

Here…


Breaking a Padlock With Two Wrenches

You know, locks don’t actually prevent people from entering a place. They are just a deterrent. Given enough time, pretty much any lock can be circumvented. But the question is time. Can you get past a lock quickly? In this case, it’s a padlock. MacGyver grabs two wrenches and uses them to pry the lock apart.

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Image: CBS/MacGyver

It’s basically a simple machine that uses torque. When he pulls the ends together, the distance the ends move are greater than the rotating distance of the tiny wrench part at the end. Since the torque is equal…


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Photo: Rhett Allain

Binary stars are cool. But if you have two stars interacting with a gravitational interaction, there are technically 6 coordinates you need to deal with (3 vector components for each star). It’s possible to reduce this to an equivalent 1 dimensional problem, but I’m not going to go over that today. Instead, I’m going to show you two things: how to calculate the initial conditions for stable orbits and how to model a binary system in python.

Let’s get started.

Initial Conditions

Suppose we have two stars (because it’s really hard to have a binary star system with only one…


I’ll be honest — there’s a lot of biochemistry in this one and I’m just a physicist.

Could Snake Venom Be Used for Cancer Treatment?

This is really the key point in this episode. MacGyver is collecting snake venom (with his DIY jar and plastic membrane) to be used for research. So, is this even legit?

Yes — it’s true that snake venom can be used in medicine. It’s really crazy if you think about it. Something that is normally dangerous can be used to heal.

Pole Vaulting

The key to pole vaulting is to use your horizontal velocity to…


Suppose you want to make a periodic wave — maybe it’s for a music synthesizer or something. Whatever you need the wave for, it turns out the easiest wave to make is a sine (or cosine) wave. You can get a sine wave by taking only the vertical component of a point on a circle rotating at a constant angular velocity. Like this.

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Animation: Rhett Allain

Yes, I made this animation with Glowscript — here is the code in case you want it. But what if you want to make a different period function. Let’s say you want to make a square wave…


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Photo: Rhett Allain. A view of New Orleans from across lake Pontchartrain proves the Earth isn’t flat

Scene: Two humans (A and B) meet near the water cooler at work. Or maybe they are just talking on the phone. I don’t know.

A: My parents finally got the vaccine for COVID. Too bad I can’t get it yet.

B: Oh? That’s too bad. Maybe you will get it soon.

A: Are you going to get it this month?

B: Me? Ummm….no way. I’m not putting that thing in my body. No thank you.

A: You don’t want the vaccine? Shouldn’t you get it?

B: Do you know how many people have DIED from the vaccine?

A: I’m…

Rhett Allain

Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. Former WIRED blogger.

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