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What happens when you take some basic, introductory physics and apply them to cool things you see? Dot Physics happens. This blog looks at movies, experiments, demos and other topics typically aimed at the introductory physics level.
Rhett Allain is an Associate Professor of Physics at Southeastern Louisiana University. He
enjoys teaching and talking about physics. Sometimes he takes things apart and can't
put them back together.
Category: Content
It is that part of the semester where the Right Hand Rule (RHR) comes out. Really, the best part is the students taking the tests. They make all these funny motions with their hands. That makes tests more entertaining (for me) than they usually are.
Posted by Rhett Allain at 6:06 PM • 17 Comments • 0 TrackBacks
Category: charge
Suppose there were two point charges, both positive but one is held in place. If I hold the other point charge a distance r away from the other charge and let go, what will happen?
Posted by Rhett Allain at 5:31 PM • 5 Comments • 0 TrackBacks
Category: charge
In this most basic form, the energy is just kinetic energy (if you are not going near the speed of light). BUT...if you have a force that is conservative (meaning the work done does not depend on the path you take), then you can make it a potential energy and move it to the other side
Posted by Rhett Allain at 1:12 PM • 2 Comments • 0 TrackBacks
Category: Content
Really, just about the entire semester course is about the electric and magnetic field. Both of these are easiest to represent as vectors. So, you pretty much need to know how to deal with vectors.
Posted by Rhett Allain at 6:46 PM • 0 Comments • 0 TrackBacks
Category: Content
Well, you are probably already familiar with this idea of the gravitational force. Guess what? "g" is the gravitational field. Basically, it is the force per unit mass due to the Earth. This is only approximately constant.
Posted by Rhett Allain at 4:27 PM • 2 Comments • 0 TrackBacks
Category: Content
How would I explain this? I would start by saying that velocity is relative. Here is the definition for velocity:
Posted by Rhett Allain at 10:45 PM • 0 Comments • 0 TrackBacks
Category: Content
Coulomb's Law is a model for the forces between two charged particles. Here is the model.
Posted by Rhett Allain at 6:50 PM • 5 Comments • 0 TrackBacks
Category: Content
I was thinking about some experiments that deal with friction and I wanted to show something with a force probe. The problem is that most people don't have one of these. So, I decided to try and make one out of simple things. In this case, I am using some straws, a rubber band and some paper clips.
Posted by Rhett Allain at 8:06 AM • 9 Comments • 0 TrackBacks
Category: Demo
Same thing, but I put one of these cheapo spectral glasses in front of the camera. This splits the light into different colors. You can see that when the laser is pointing on most things, only green light is reflecting off. However, on some objects (orange plastic and pink plastic) other colors are present also.
Posted by Rhett Allain at 10:35 AM • 19 Comments • 0 TrackBacks
Category: Content
The following is a collection of some of my posts that can be put into a simple and quick textbook-type thingy. I am not really sure you would call this a textbook, but maybe you would. This does not include everything you would normally find in a traditional textbook, but clearly it is not traditional. I tried to keep it to just the fundamental ideas. As I write more stuff that is appropriate, I will add it.
Posted by Rhett Allain at 9:29 AM • 6 Comments • 0 TrackBacks
