tingilinde

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is working in your kitchen a pain in the back?

Thirty six inches

Almost all countertops in the US are 36 inches high.   It is sketchy how the standard came to be, but it is a very convenient number and it is approximately correct for the average woman in post WWII America.

This turns out to be somewhat too low for me and way too low for a friend who gets lower back pains bending over. Last year I posted a challenge to find a good design for an adjustable  height working surface, but not many responses turned up (here and here)

Rules of thumb for standing work surface height often state the surface should be at or a bit below elbow height for light work, two to four inches above for precision work and four to six inches below for heavy work.  

Some more careful studies in 1970 (Ward and Kirk) studied women preforming three tasks and made the following recommendations:

group A  tasks performed above the worktop (peeling vegetables, beating and whipping in a bowl, slicing bread) 119 mm below elbow height

group B   tasks performed  on the  surface (spreading butter, chopping ingredients) 88 mm below elbow height

group C  tasks involved downward pressure (rolling pastry, ironing) 122 mm below elbow height

Group B was deemed most important for general kitchen work,  and a weighted average of the three groups suggested a general purpose work surface should be about 100 mm below the elbow.

Using elbow height distributions for men and women in about 1970 and subtracting 100 mm to find work surface heights the following recommendations were made (these are barefoot heights .. you should add shoe height)

5% female 855mm [33.7"]
50% female 930mm [36.6"]
95% female 1005 mm [39.6"]

5% male 930mm [36.6"]
50% male 1015mm [40.0"]
95% male 1105mm  [43.5"]

The barefoot range for 5% females to 95% males is not exactly covered by the fixed 36" standard counter top, although the 50% female 1970 female is very close to the 36" countertop.

Since 1970 other studies suggest two inches below elbow height is a better for general light kitchen work and four inches for heavier work, but numbers between two and four inches are probably ok for most people.  A more detailed analysis requires additional measurements and strength measurements for various tasks.  

There are über-expensive motor driven adjustable countertops, but a less spendy solution may be something custom height or perhaps two custom heights if a couple likes to work in the kitchen, but is not matched on height. 

If you are contemplating something  custom for yourself, put on the shoes you would wear when cooking and stand upright - relaxed but with the best posture you can muster.  Have someone watch to insure your posture is good and have them measure your elbow height.  Subtract four inches and put books or magazines on your present countertop if the number is greater than thirty six inches and see what it feels like to work at that level.  You might want to fine tune a bit before spending money.  If it is lower,  peform the same experiment but from a lower table (a kitchen table or a bathroom counter) as a base surface.  

Now the trick is what to do if you already have a counter and aren't going to remodel your kitchen.  Stay tuned - there is a project underway.

enjoying the night sky

I have a great fondness for the night sky.  When I was a teenager, telescopes were the best way to see it.  I had an 8" Newtonian that was about the size of a human body and weighted well over 100 pounds with its mount.  It gave wonderful views for years, but portability wasn't a strong suit.

At college the physics department owned two Questars - a 3.5" and a 7".  These were extremely well designed maksutovs with beautiful optics.  The focal length was long and they weren't the best thing for simply star gazing, but that didn't stop me from checking it out many times and hauling it into the mountains.  The 7's tube in a fiberglas packing case weighed about 45 pounds and the mount and battery another 80.  Two of us would distribute things so we only had about 60 pounds each on our packs and off we'd go. 

A 80 pound portable mount with a 25 pound tube isn't exactly the most stable thing in the world, but I discovered a good mount with a 35 mm camera an the right sort of lens is a nice way to capture the beauty of the milky way.   It turns out much of what is really beautiful takes up a lot of sky and a telescope is usually designed to look at a very small area of the sky.  There are still many beautiful things to be had with telescopes but never short change your own eyes, a pair of binoculars or a small wide angle telescope.  

An idea combination is a really dark area (the mountains in the desert southwest are good candidates) and your eyes and possibly a nice pair of image stabilized binoculars (10x50 or 14x50 canons are really nice - I have a pair of 15x50s).  Given a choice of nice equipment or a dark site, I'd take the dark site any day.

Recently some interesting field mounts have been appearing.  Combine one of these with a good wedge, a quality 100 mm f5 refractor, a great objective and you might have the perfect backpack telescope ...  but your naked eye or binoculars and a good lawn chair may be even more fun.

And anyone can learn the sky if you can see at least the brightest few hundred stars.  Try a planetarium program to help out a bit.

But those of you who are in areas where you can easily get to a beautiful night sky - go out and look up.  Try the Pleiades with some binoculars and see if the view doesn't knock the wind out of you.

when pack ice goes packing

A Quirks and Quarks segment on a major change in the nature of the arctic ice sheet. (mp3)

Things are changing ... something that isn't picked up from satellite observations.

the maple leave rag (sic)

CBC's excellent Quirks and Quarks had a piece on the failure of the regulatory process and Canada's Maple isotope reactors. (mp3) There is a worldwide shortage of medical radioisotopes caused by the shutdown of an ancient Canadian reactor that is impacting the way medicine is done.  These reactors would have solved the problem, but ...

Q&Qs is what mostly takes me through Saturday morning rowing... one of the best science radio shows in the world.

reasoning with cross winds

Bob points out a video showing some crosswind testing of a Boeing 777 and 747SP in Brazil. Standard stuff for sailplane drivers, but impressive with heavy aircraft.

Here are some technique notes for a similar airliner.

a line of geysers at the south pole

Of Enceladus...

Cassini flew by that small, but geologically very active, moon of Saturn a few days ago and some remarkable photos are appearing on the mission site.

david archer's global warming class

David Archer has posted his lectures for global warming class he gave for non-science majors at U Chicago this quarter.  I haven't watched them, but they should be excellent base on the fact they are from him.

Science literacy is terrible in this country - offerings like David's are a step in the right direction, but I'm guessing they will still be too taxing for most.

two planetarium programs

Stellarium is very good and is multiplatform and has the advantage of being free.  It is excellent for many users and perhaps any casual user.

Another very nice program is Voyager from Carinasoft ..  it is currently on sale for $80.

In both cases - read the manual!

nailing back pain

Try sleeping on a bed of nails...

or at least the modern Swedish equivalent.

The basic idea appears to be sound, but I think I'd have to try it.