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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.
January 30, 2009
Category: physics
Initially, there is something (the box) with water inside. Through some process, the water is shot out of the box. The initial total momentum (water plus box) is zero (vector), so the final total momentum is zero (since there are no external forces). Note that the water will be going much faster than the box if the water has a smaller mass.
Posted by Rhett Allain at 11:38 PM • 3 Comments • 0 TrackBacks
Category: physics
However, in the episode 900 there was an email from a listener regarding LHC and black holes. The emailer claims that a massive black hole would mess up Earth's orbit. This is not quite true.
Posted by Rhett Allain at 10:32 AM • 1 Comments • 0 TrackBacks
January 29, 2009
Category: physics
I saw this on Hack a Day, but I am sure it has been posted in other places also (seems like something that would be on Swans on Tea). Check it out. Amazing New Water-Powered Jet Pack - Watch more...
Posted by Rhett Allain at 9:19 PM • 0 Comments • 0 TrackBacks
Category: physics
I really didn't want to post this, but I am going to anyway. I used ScreenToaster.com to make a screen capture movie (with audio) of a tutorial on spreadsheets.
Posted by Rhett Allain at 4:16 PM • 1 Comments • 0 TrackBacks
January 27, 2009
Category: physics
We have all seen the Kobe Bryant video of him jumping over an Aston Martin - this keeps coming up on the Internet. There has been vast discussions of whether this is real or fake. I will do my best to examine the evidence. In short (in case you don't want to read the whole thing) Kobe can most likely really jump that high, it is possible that there was some perspective trickery involved.
Posted by Rhett Allain at 11:02 PM • 8 Comments • 1 TrackBacks
Category: grades
Should you grade on a curve or not? If you are student, the answer is clear: go by whatever the instructor does.
Posted by Rhett Allain at 10:08 AM • 6 Comments • 0 TrackBacks
January 25, 2009
Category: physics
When you pour a beer, there is this foamy top called the head. The size of the head decreases over time. What is this process dependent on? Clearly, little bubbles of beer are popping. Does each bubble have an equal probability of popping? Do only the bubbles on the top (or bottom) pop?
Posted by Rhett Allain at 9:23 AM • 5 Comments • 2 TrackBacks
January 22, 2009
Category: science
When is the Sun directly overhead?
Posted by Rhett Allain at 3:47 PM • 5 Comments • 0 TrackBacks
January 20, 2009
Category: physics
So, you are taking a college science course. Maybe it is physics, maybe it is chemistry, maybe its a lab. Either way, you always end up with these problems that involve unit conversions. You think you have the hang of it, but sometimes you make some mistakes. Here is my explanation for converting units.
Posted by Rhett Allain at 10:18 AM • 1 Comments • 1 TrackBacks
January 19, 2009
Category: physics
After an unusually high previous power bill, they checked the electric meter half way through the month. The meter said they had used 90,000 kilowatt-hrs of electricity. That is a lot of energy. It is also a lot of money. If I estimate 10 cents per kilowatt hour (the prices varies in space and time), this would be a $9,000 bill.
Posted by Rhett Allain at 10:06 AM • 5 Comments • 0 TrackBacks
