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Larry Haun: Newton's second law v^2=u^2+2*a*s And F=ma Assume the time of strike is same, Direct proportion to  -Hammer weight (mass) -acceleration -square of distance of strike. Turkish woodworker  Veysel Çelik : Time:~1/4 sec Travel:~50cm Nail:50 mm Hammer: 284g(10 oz) Timber: 3x4cm 松木或樟木,(畫框木） So the force is 11N In Tennis serve: So there's no "velocity hammer", but acceleration and how high you strike. Higher/longer is the strike, the square of increase is your driving force. And it doesn't matter which material ( titanium or steel) of hammer head is used Hammer weight, choose one as long as you can handle, not strain to your waist and elbow.  You should feel good in hand and good balance. Some heavy ones just too "head heavy". Also the manufacturers offer heavy head with shorter handles, with good reasoning. For me the max is ~16 oz Reference: Toppr

openpyxl is a Python library to read/write Excel 2010 xlsx/xlsm/xltx/xltm files. It was born from lack of existing library to read/write natively from Python the Office Open XML format. All kudos to the PHPExcel team as openpyxl was initially based on PHPExcel. Pypi Realpython Youtube

 3月20 03：06:25.4 UTC 11:06:25.4 HKT

Plumb bob is actually a type of pendulum. Movement is determined by Simple harmonic motion period of the pendulum was approximately  2*Pi*sqrt(l/g) Damping  and critically damping  Water vs air: 40 sec vs 60 sec  Dry and viscous damping Flapping of bird pendulum   By air Diameter of string  Helm string麻繩 vs nylon line: 40 sec vs 70 ~80 sec Eddy current and  Magnetic damping Reinventing ideas   Initial experiment with an existing plumb bob and two simple magnets is not too successful, needs more fine tuning. Otherwise you are making a chaotic pendulum instead. TBD. Another YouTube   Xmdemo  by varying the magnet to damper distance Magnetic braking(eddy current) with copper plate: ME230 Reverse  "Laser" plumb bob , laser firing upwards Laser firing downwards： Shinwa  ， 易之力 EZX-038 Sikana  , using a wooden block with hole Plumb bob should be as close to wall as possible, almost touching. Stackexchange Isaac Plumb bobs  ,...

 GUI: CPU: Renesas (Hitachi) superH SH3 or SH4 Fx9860GII support OS update This CPU has been used as a LCD controller IC Forum Planet casio Codewalrus Wiki Comparison chart Overclock the fx-9750 , hackaday .  Using gcc E-Gadget Link of links Firmwares   3 pin SLIP

 地面級咀線 台英： 柱躉： 注意不是直角，而是斜向第一級 斜板： 突出幾個 不用鋸成“貼邊”.拆板時用鎚仔打掉突出部份。 Assume: Common dimensions of 私樓消防後樓梯。 級面225  級高175 級咀線37.875 degrees  級距285.044mm 級咀 踢腳距離138.137 2000+50批盪=2050釘模尺寸 樓梯通道不得少於1050 樓宇條例 每级高度不得高於175 每级深度不得淺於225 每展樓梯不得多於16級 樓梯房的高度不得少於2050mm Kknews Jishulink

  Method A: 劃格仔 Method B: 劃級咀線，級底線 Eg this case, 第8級， ie 這展樓梯最高的一級： 展寬225x8=1800 展高 175x8=1400 用勾股定理，or by measurement,去定每一級咀的距離b 級咀 to 上斜：80 ~90 級咀 to 級台底：~ 295

 

 4組件

 >800個，2條花籃 <680個，1條花籃

  營造法式 李誡 （北宋崇寧二年1103） 壕寨制度卷三 望筒長一尺八寸，方三寸〈（用版合造）〉兩罨頭開圜眼，徑五分。筒身當中兩壁用軸安於兩立頰之內。其立頰自軸至地高三尺，廣三寸，厚二寸。晝望以筒指南，令日景透北。夜望以筒指北，於筒南望，令前後兩竅內正見北辰極星然後各垂繩墜下，記望筒兩竅心於地，以為南則四方正。 景表版 望筒 水池景表 天文訓 三表測向法： 玉圭  游表，定表 日間： 夜間： 到底哪星是北極星： 長安： 漢朝： 中，日比較 採用與棄用 Taikyokuden era 太極宮 的時代 Reference: 古天文部屋 Ctext  卷二十八：15 度日出日入以知東西；南視定，北準極，以正南北。 考工記： 太陽中位法 北極星上中天法 周脾算經中的北極星 Thepaper 羅盤與建築方位  Zhihu Wiki 西安半坡遗迹中，发掘出远在6000年的原始公社部落建筑残存旧址，发现所有的房屋朝向及门三都大致是南向的 林安泰古厝 青龍白虎