Recent content by jrmichler

Yes, this is a well known effect. Search terms p51 mustang radiator thrust will bring up several good hits. The Wikipedia article is a good place to start, and suggests that Meredith effect is an even better search term.

When deer see apples overhead, they can stand on their hind legs to get them. That tree had about 90 lbs of apples this year. I estimate that the food shelf got 40 lbs, the deer got 10 lbs, and I ate 40 lbs. Yes, I eat a lot of apples. Always have.

Same here, except ME.

Been almost 50 years since I took basic heat transfer in college, so I had to do some homework in order to do heat transfer film coefficient calculations last week. Some general rules of thumb for corrugated plastic signboard: Channels vertical, open ends = maximum heat transfer (worst...

Here's a couple more terms. Plastic solid is a solid with a yield point. After yielding, it will continue to deform without limit. When the stress is removed, it stays in position. Bingham plastic is a solid with a yield point. After yielding, it behaves as a viscous liquid.

Much of the hot air does not actually add heat to the surface, but it does give a good upper limit to the amount of heat needed. Using the factor of 200 * 0.15 m##^2## = 30 m##^2## area for the mirror. That's a 6 meter diameter mirror for the upper limit. My steady state calculation results...

I just finished doing some heat transfer calculation for something else. It's been a long time, so getting back up to speed took time. Having done the studying, I could not resist doing some calculations for tree burning. Making the following assumptions: Emissivity = 1.0 Temperature of...

I have been collecting articles and papers on lifestyle vs health. Here's some about dementia: Healthy lifestyle reduced risk of Alzheimer's by 60%: https://www.nih.gov/news-events/news-releases/combination-healthy-lifestyle-traits-may-substantially-reduce-alzheimers Exercise produces hormone...

A rule of thumb is that a typical normally aspirated automobile gas engine burns 0.5 lbs of gasoline per horsepower-hour. Since gasoline has a heat content of 20,000 BTU per pound, and one horsepower is 2545 BTUH, that is an efficiency of 25.5%. Modern engines are more efficient. From...

I calculated the sun image diameter assuming: Sun 865,000 miles diameter Sun 93,000,000 miles distant Focal length 150 feet Perfect optics And got a sun image 17 inches diameter. The next question is how much energy per unit area is needed to burn wood. The necessary mirror area can be...

About 1980, my grandmother had her wash machine plugged into one of these adaptors. I asked her if that really worked, and she said that it only smoked during a heavy load. So we had a work party the following weekend. My father, brother in law, and I completely rewired her basement with...

You are correct. For moving 4000 lbs, you need some math. Here is how I solve this type of problem. Step 1: Sketch an acceleration - velocity - position diagram that includes all available information. A pencil sketch is good enough at this stage. Your diagram would start as follows: You...

This video of two hungry fawns feeding from their mother was taken looking out my living room window using a cell phone camera. We only mow grass around our house. The unmowed part has not seen a lawnmower since 1995. That's why it's popular with deer. Does like to drop their fawns on our...

These spam posts get moderated so fast that most people never see them. The moderators have a special button that deletes the post and permanently bans the spammer. I have not counted, but a rough estimate is a dozen or so "status update" posts per week. We have roughly 50 moderation...

Just ONCE, I wanted to see a post titled Status Update that was not a blatant, annoying spam post by a new member. So here it is. Today was a good day here in Northern Wisconsin. Fall colors are here, no mosquitos, no deer flies, and mild temperature, so my morning run was unusually nice...