Blog Profile / Dot Physics

How Long Would It Take to Fall Through the Earth?

I didn’t see the latest version of the movie Total Recall (2012). However, I heard some people talking about the elevator scene. Here is what I gather from the plot (which could be wrong). There are essentially just two cities on Earth in the future. The only way to get from one city to the [...]

An Analysis of a Perpetual Motion Machine

Everyone loves perpetual motion machines. They are a representation of the highest level of creativity in finding loop holes in the laws of physics. Let’s take a look at this one. What is a perpetual motion machine? Wikipedia defines it as a machine that has a continuous motion without any energy inputs. Of course, this [...]

Should Students Use Cameras in Class?

If you have been in a lecture hall in the past year, this sight might be familiar. You look up at the class and there they are. Students with their phone out. Either taking a picture of the question slide you just asked or video recording a solution. Is this bad? Honestly, for me, I [...]

How Bad Was the Spin During the Stratos Jump?

Although the Red Bull Stratos jump is over, the physics goes on. In case you missed it (I don’t know how), let me recap: Felix Baumgartner rides a balloon up to 128,000 feet altitude – of course he has to wear a space suit. He jumps (falls) out. During the fall, he goes faster than [...]

What Is Daylight Savings?

Oh sure, you know what it is…but do you really know what is going on? There is some interesting physics here. What is Daylight Saving Time? Let me start with the Sun. Suppose you were to watch the Sun (but not look directly at it, that is a bad thing) over the course of a [...]

An Analysis of Fister’s Line Drive Head Hit

Tigers’ pitcher Doug Fister did not seem to be seriously injured after this line drive baseball hit to the head. So, that’s good. Also, this seems like the video would allow us to answer some questions. In particular, how hard did the ball hit his head? Usually, this is the question most people want to [...]

Portal Gun and Magnetic Levitation

This is just plain cool. If you would like some more details, check out the post at Hack a Day. The companion cube levitates with magnets. But this brings up a great point. Why can’t you use plain old magnets to get something to levitate. And by levitate, I mean be in stable equilibrium such [...]

Could You Start Your Car With D-Cell Batteries?

I seem to recall a question like this in an introductory physics textbook. The basic idea was that your car has a 12 volt battery that is used to start the engine, right? Well, 8 D-Cell batteries in series will also make a 12 volt battery. However, not all 12 volt batteries are the same. [...]

Super Fast Ping Pong Ball Gun

This is Harold Stokes from BYU and he made a ping pong ball cannon. Here is his very entertaining demonstration. It’s a little long, but a great presentation. How does this work? The basic idea is to use the atmospheric pressure on one side of a ping pong ball (with no pressure on the other [...]

What is the Speed of Sound?

This seems to be the most common discussion regarding the recent Red Bull Stratos Jump. Unless you have been living under a rock lately, you have probably seen the awesome jump from 128,000 feet. Here is a great summary video to get you pumped up. The official fastest free fall speed was reported as 373 [...]

Red Bull Stratos: Why Didn’t Felix Free Fall for 5 Minutes?

Well, he did it. Felix jumped out of a balloon 128,000 feet above the Earth as part of the Red Bull Stratos jump. Of course, I was watching this video live. One thing interesting at the end was the altitude. It seems the plan was to jump from 120,000 feet – but the balloon got [...]

Moving vs. Accelerating

First, I would like to applaud this science museum for a creative ad campaign. In short they placed interesting “facts” around the city such as a visual display of how much snot everyone swallows each day. Funny and interesting. Of course, I wouldn’t make a post unless I had something to complain about. I am [...]

Numerical Calculations as a Physics Assignment

I love python. I’m not ashamed to admit my feelings. One of the things I attempt to convey in my introductory physics courses is the notion that numerical calculations are cool. Of course, by numerical calculations I mean taking a problem and breaking it into many smaller (and simpler) steps. These small steps can then [...]

Watch the Red Bull Stratos Jump Live

If the weather holds up, Felix Baumgartner will soon step out of a capsule 120,000 feet above the ground. It should be awesome. What’s even better is that you can watch it live online. How? There are some options for viewing the jump. Probably the easiest is the Red Bull youtube channel – http://www.youtube.com/redbull which [...]

The Physics of the Red Bull Stratos Jump

Iron Man 3 and the Human Chain

Here is a picture from the filming of Iron Man 3 (from shockya.com – or maybe it looks like Star News Online was the first to get the pictures). I have no idea what is supposed to be going on here, but I can guess. It looks like Iron Man is pulling some people somewhere. [...]

Is This Answer Crazy? Maybe.

It started with a short in-class question. If you know the mass of one mole of platinum and the density of platinum, what is an estimate for the diameter of one platinum atom? Of course, this calculation involves some assumptions. The primary assumption is that the platinum atoms form a cubic lattice such that the [...]

How Big Are the Bad Piggies?

Now that Bad Piggies is out, you know I have to do some analysis. What is Bad Piggies? In short, it is the next game from Rovio, the makers of Angry Birds. In this game, you control the pigs instead of the birds. Instead of using a sling shot to fling birds, you build contraptions [...]

How Big Is the xkcd Click-Drag World?

Click for the full xkcd experience xkcd did it again. This is an amazing image. Yes, you have to click and drag around the map. It really captures the spirit of exploration, doesn’t it? Oh, don’t cheat and search for the whole map at one time. That’s no fun. If you actually take the time [...]

Hurricane Isaac and Time Travel

Due to the recent Hurricane Isaac, we missed a few days of classes. Oh? Classes were missed? There MUST be a plan to account for all required hours during the semester. This means that each faculty must document his or her plans to make up the missed classes. Many will choose to have some type [...]