# Rutherford scattering toy, and more

My friend Konrad showed me this awesome toy he made. I know it doesn’t make sense yet, so let me explain. Basically, you take this marble and roll it down the tray through the pegs. The pegs sort of randomize where the marble rolls through the hidden section. Inside the hidden section, it looks like…

# How a silly online guessing game works

I got this question. How does this game work? Really, this is one of those silly things that gets forwarded a lot. It is called Regifting Robin. The basic idea is: pick a 2 digit number, like 37 subtract both the number in the tens place and the number in the ones place from the…

# Accelerometer Version-2

So, I built a new accelerometer. Why? The jelly-jar one was just not doing it for me. Plus, the cork was starting to make the water all yellowy. It was a good start, but I can do better. What was wrong with the jelly-jar one? First, it didn’t let the cork move very far before…

# Labs to not do – mechanical equivalent of heat

Note to self: don’t do the mechanical equivalent of heat lab again. It doesn’t really work that well and there are better labs to do. So, what is the mechanical equivalent of heat lab? It is actually a pretty cool idea. Take and object and drop it. What happens to the kinetic energy the object…

# Accelerometers – and build one yourself

This has been on my list for quite some time. Really, it must be since i posted about measuring acceleration in free fall with an iphone. So, this post will be all about accelerometers. How does an accelerometer work? Really, an accelerometer measures force some way on a known mass. Let me show an extremely…

# A demo for the color black

What do you see when you are in a completely dark room with no lights? That is a great question to ask. It can bring out some interesting ideas. Anyway, here is an easy demo to show the color black. The basic idea is to build a box that has a small opening. Here is…

# iPhone in a rocket

My brother found this, but he is too afraid of the internet to post something in the comments on my previous post about acceleration and the iphone. It turns out that this too awesome to just be in a comment. It deserves its own note. Anyway, I was looking for acceleration data from the iPhone…

# Moment of Inertia Demo

When I was talking about balancing a stick, I mentioned the moment of inertia. Moment of inertia is different than mass, but I like to call it the “rotational mass”. What does mass do? Things with larger mass are more difficult to change their motion (translational motion). A similar thing is true for the “rotational…

# Cool Quote from an old Scientific American

Some time ago I was looking for materials to possibly build a foucault pendulum. Of course the first step is google. There was a site that suggested two old issues of Scientific American, and it happens that we have tons of old Scientific Americans in the store room. I found the two that I needed.…

# Water Bottle Camera Mount for stability

Better technology sometimes causes problems. In this case, technology has made video cameras really small. Small? That’s a problem? Well, the problem (as I discussed previously) is that small cameras are not stable and make “shaky” videos. Well, then increase the mass of the camera – simple. I wanted to test this idea and make…