# Why Blog?

My brother started blogging. I encourage this kind of behavior. His blog (bluerope.org) is mostly about cocoa programming (which he seems to be fairly competent at). Anyway, I wrote this comment on his first post. “I applaud your effort to begin a blog again. If everyone had a blog, this world (the internet) would be…

# RP 10: Centripetal Force, Centrifugal Force – what’s the deal?

A couple of commenters expressed concern over the use of centrifugal force after my rant on the use of the word force. So, what is the deal with these two terms? Are they ok to use? Are they real forces? First, are they real forces? It depends on what you mean by real. What is…

# RP 9: Error propagation and the distance to the Sun

Some time ago, I wrote about the awesome things the Greeks did in astronomy. Basically they calculated the size of the Earth, distance and size of the moon and distance and size of the sun. The value obtained for the distance to the sun was a bit off, but still a bang up job if…

# Battery to power a house for a week

I saw this post about Panasonic’s home battery. The claim is that this will lead a battery that can power a house for a week. I wonder if I can estimate how big this battery would be. First – to estimate the energy a house consumes. My first approximation is that you could probably run…

# RP 8: The price of a piece of LEGO

This idea comes from my friend Thomas. His son is like mine in that they both think LEGO are awesome, and they are correct. For some reason, Thomas decided to calculate the price per piece of LEGO in each set. To promote repeatability, I decided to do this also. Looking at the catalog at LEGO.com,…

# LEGO plus Slinky = Physics

What happens when your kids won’t give you a turn on the Wii? Simple. You take their LEGO bricks and their slinky and do some physics. I will keep this simple. Basically, I created a slinky holder out of LEGO pieces and added LEGO bricks to the end to stretch it. Here is the video.…

# 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).…

# RP 6: Throwing a fooball, Part II

In part I of this post, I talked about the basics of projectile motion with no air resistance. Also in that post, I showed that (without air resistance) the angle to throw a ball for maximum range is 45 degrees. When throwing a football, there is some air resistance this means that 45 degree is…

# RP 5: MythBusters: How small could a lead balloon be?

On a previous episode of The MythBusters, Adam and Jamie made a lead balloon float. I was impressed. Anyway, I decided to give a more detailed explanation on how this happens. Using the thickness of foil they had, what is the smallest balloon that would float? If the one they created were filled all the…

# RP 4: More on the movie Up! (or Upper)

So, analysis of the movie Up is pretty popular in the blogosphere. Figure I might as well surf the popularity wave. So, I have a couple more questions. The most important thing to estimate is the mass of the house. I am going to completely ignore the buoyancy of the house. I figure this will…