# Density of Wood

This isn’t much – really it is part of another post I am working on. The point of this post is to calculate the density of this piece of wood. Really, there is a reason for this. I saw this little stick (sticklette?) and noticed that it was very cylindrically shaped. So, what if I…

# RP 7: Cool things the Greeks did in astronomy

One of things I like to think about in science is “how do we know that?” It is interesting how one thing builds on another. This is a story of how the Greeks estimated the distance from the Earth to the Sun (an important idea in the development of the model of the solar system).…

# Uncertainty and Video Analysis

This is for commenter JimP. How do you take into account uncertainty when using video analysis? A great question. The first thing to think about is where does the uncertainty come from? My first guess would that it would be from the user. Where does the user click? Is it right on the object in…

# Parallax, what is it good for?

Very simply, parallax is an apparent motion of an object due to a change in observation position. Let me start with an example. Here are two photos. I took a picture of the cabinet in the background from two slightly different positions. In the foreground is a clone trooper that did not actually move. I…

# Cool things the Greeks did in astronomy

One of things I like to think about in science is “how do we know that?” It is interesting how one thing builds on another. This is a story of how the Greeks estimated the distance from the Earth to the Sun (an important idea in the development of the model of the solar system).…

# Significant figures what are they for and what do they have to do with uncertainty?

Suppose I am working on a problem and I wish to calculate the density of something. I measure the mass to be *m* = 24.5 grams and the volume is *V* = 10 cm3. In this case the density would be: ![Sigfig 1](http://scienceblogs.com/dotphysics/wp-content/uploads/2008/09/sigfig-1.jpg) ALERT! ALERT! ALERT! This is not a test!!!! Something is drastically wrong!…