# Circular Motion Lab

Sometimes it is difficult to come up with new labs. Ideally, a lab should show use some of the basic physics principles as well as have something the students can measure. What to do with circular motion? I don’t know how I forgot this, but here is a lab I used to do as an…

# A surprisingly fun demo

You know I like demos, right? This one is quite fun to do even in a class. The basic idea is to take a bucket of water and swing it around in a circle over your head. Simple, but if you have never done this one, it can be a little intimidating. Here is an…

# 5th Gear Loop the Loop

Maybe this is a little old (in internet age), but it is a great example. Here is the Loop-the-loop stunt from the show Fifth Gear. I like this. First, it is a bold stunt. But also, there is some good physics here. Though, most importantly, the Fifth Gear producers were kind enough to include a…

# Tides. Why are they so hard?

Every introductory astronomy text and most intro physics texts talk about tides. The usual explanation is something along the lines of: The moon exerts a gravitational force on the Earth and all the stuff on the Earth. This force decreases with distance (1/r2). Thus the moon pulls greater on one side of the Earth than…

# Playing with a merry go round

Thanks to reader Cleon for notifying me of this video on youtube. Check it out. First, some notes. I am sure you noticed that the aspect ratio is incorrect (at least that was the first thing I noticed). The boys must have made a 16:9 video, but then uploaded it to youtube as a 4:3.…

# Basics: Centripetal Acceleration

pre-reqs: vectors, kinematics I haven’t done a “basics” topic in quite some time. It’s odd, I have used centripetal acceleration quite often, but I never derived the expression that I use. To get to the point, the magnitude of the acceleration of an object moving in a circle is: Also, the direction of this acceleration…

# Mythbusters and WANTED – curved bullet

I have been wanting to look at this whole curved bullet thing, but I wasn’t sure how to approach it. In case you are familiar with the myth, this is from the movie WANTED (which I did not see). Apparently, some people learn how to make bullets curve by moving their gun. Here is a…

# When the centrifugal force is the centripetal force

It’s odd that I have talked about these forces so much. First, I talked about how centrifugal forces were not real and the difference between centrifugal and centripetal forces. Then I talked about how sometimes, fake forces are good. Finally, I talked about the origin of the words centrifugal and centripetal. (note: “talked about” means…

# Centripetal vs. Centrifugal (word origins)

A student in my office temporarily confused the words centripetal and centrifugal. This started me thinking about these two words. They mean different things, but do sound and look similar. I have previously talked about the difference between fake and non-fake forces, but let me quickly define these two: Centripetal: This is the force needed…

# Video Analysis Tutorial and a cat

Cats can be entertaining – especially when they are someone else’s cat and that someone made a video. Really, this post is about analyzing video with Logger Pro (in a tutorial type fashion). I just happens that I chose this cat video to analyze. Here is the video: I am going to look at the…