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Author Archives: mathscinotes
Letter Folding for Envelopes
I still occasionally write paper letters. In fact, I had some letters to write the other day, and I realized that was doing a bit of math when I folded the letters for placement into standard business envelopes that was worth discussing here. Figure 1 shows the business envelope that I normally use. Continue reading
Posted in General Mathematics, Origami
3 Comments
How I Orient My Electrical Outlets
For years, I have mounted most my electrical outlets upside down (see Figure 1). Recently, I have started to see more folks orienting their outlets this way. I see that Finehomebuilding Magazine and the Journal of Light Construction (JLC Field Guide) recommend this approach as well. However, it is not required by the National Electrical Code. Continue reading
Posted in Construction
2 Comments
My Cub Scout Training Solves Test Equipment Corrosion Problem
We have recently experienced some laboratory failures during humidity testing that were due to corroded connectors (Figure 1). The connectors had corroded after they become wet from condensation that accumulated on the cables and rolled down to the lowest point on the cable – where the connectors were. Continue reading
Posted in Electronics
1 Comment
Venus-Like Exoplanet In the Neighborhood
I have been reading a number of articles that are reporting on a Venus-like planet (GJ 1132b) recently discovered in a nearby star system (Gliese 1132, 12.0 parsecs away). I like to work a bit with the numbers reported in these articles to determine if I actually understand what is being reported. I have to admit that I also like to imagine the day when astronomers are studying Earth-like planets around other stars. I definitely see that day coming. Discoveries like GJ1132b are particularly interesting because astronomers for a long time did not think red dwarf stars were promising for Earth-like planets. Continue reading
Screwed Wood Joint That is Totally Concealed
This is the first woodworking tool that I have seen that uses a two-part electric motor. I have encountered this type of two-part electric motor before in situations where some mechanical object needed to be rotated while contained in a completely sealed environment. In this case, the electric motor's armature has a screw thread that pulls the joint tight. See this web page for more details. I certainly can see several applications for this type of connection. Continue reading
Posted in Construction
2 Comments
WW2 Reticles
I have watched a lot of old WW2 combat footage, and I have noticed that many of the machine guns and fighter planes had similar reticles. A reticle is a fine-grid of lines used in conjunction with an eyepiece to assist in taking measurements or with accurately pointing an instrument. Figure 1 shows a reticle similar to what I have seen in numerous combat scenes. Continue reading
Posted in Ballistics, Military History
Comments Off on WW2 Reticles
Gift Wrapping Math
My sister works as an event planner/wedding planner. She wrote me an email today with the following gift wrapping question.
I need to wrap 375 boxes. 16x14x6. The wrapping paper is 30 inches wide. I say I need about 1700 feet. People are telling me I only need half that. Continue reading
Posted in Geometry, Paper Machines
21 Comments