可有大侠开课讲讲英制与公制的起源和依据
In the gravitational systems, the weight of the mass unit (pound-mass) on Earth's surface is approximately equal to the force unit (pound-force). This is convenient because one pound mass exerts one pound force due to gravity. Note, however, unlike the other systems the force unit is not equal to the mass unit multiplied by the acceleration unit—the use of Newton's Second Law, F = m·a, requires another factor, gc, usually taken to be 32.174049 lbm·ft/lbf·s2 = 32.174049 lbm/slug. "Absolute" systems are coherent systems of units: by using the slug as the unit of mass, the "engineering" FPS system avoids the need for such a constant. The SI is an "absolute" metric system with kilogram and meter as base units.-----From Wikipedia
https://en.wikipedia.org/wiki/Pound_(force)#Definitions
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听八爷讲当年俄国人造飞机，将单位改成米规英制，其实质是什么？
在材料力学方面，老美的教材要求学生掌握两种单位。
A Careful Balance Between SI and U.S. Customary Units Is
Consistently Maintained. Because it is essential that students be
able to handle effectively both SI metric units and U.S. customary
units, half the examples, sample problems, and problems to be
assigned have been stated in SI units and half in U.S. customary
units. Since a large number of problems are available, instructors can
assign problems using each system of units in whatever proportion
they find most desirable for their class.
——引自 MECHANICS of MATERIALS
咱觉得吃饱撑着可以尽可能背诵数字,早期电话不普遍,高中时校内某英文老师视力能见度只有一呎深,没事拿起本市电话簿背诵,说某户姓名他能告诉你电话号码,过几年用户大增随之增位数就不管用了
你问雨人4位数乘4位数,他毫不思索说出正确答案,因为他见过这数字 恁老厮 发表于 2016-1-29 14:06 static/image/common/back.gif
咱觉得吃饱撑着可以尽可能背诵数字,早期电话不普遍,高中时校内某英文老师视力能见度只有一呎深,没事拿起本市 ...
不错的引例哈
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