Section outline

  • lesson content

    How do you measure something really, really small?
    ::你如何测量真正,非常小的东西?

    If we are talking about a , then not with a ruler. Units must exist that can describe sizes many times smaller than the smallest marking on a ruler.
    ::如果我们谈论的是一个, 那么不是一个标尺。 单位必须存在, 单位必须能够描述大小, 比标尺上最小的标记要小很多倍 。

    Units of Measurement
    ::计量单位

    The measurements that scientists use are based on the International System of Units (SI), which is a form of the metric system. The term SI is shortened from the French term Le Système international d'unités . It is the world's most widely used system of units, both in science and business. It is useful to scientists because it is based on multiples of 10. The SI was developed in 1960 from an older metric system and is used in almost every country.
    ::科学家使用的测量方法以国际单位体系为基础,国际单位体系是衡量制度的一种形式,国际单位体系一词从法国术语“国际统一”中缩短,是全世界在科学和商业领域最广泛使用的单位体系,对科学家有用,因为它基于10倍的倍数。 1960年,国际单位体系从一个较老的衡量制度发展而来,几乎在每个国家使用。

    The SI is not static, as the technology of measurement progresses, units are created and definitions are changed through international agreement among many nations. The international system of units is made up of a seven base units, shown in the SI Base Units Table . From these seven base units several other units are derived.
    ::职业妇协不是静态的,因为测量技术不断进步,许多国家通过国际协议创建了单位,并改变了定义,国际单位系统由七个基本单位组成,如职业妇协基地单位表所示。

    Name Symbol Quantity
    meter m length
    kilogram kg mass
    second s time
    ampere A electric current
    kelvin K thermal energy (temperature)
    mole mol amount of substance
    candela cd luminous intensity

    A prefix may be added to SI units to make a multiple of the original unit. An SI prefix is a name or symbol that is put before a unit of measure (or its symbol) to form a decimal or a multiple of the unit. For example, kilo - is a multiple of a thousand and milli - is a multiple of a thousandth, so there are one thousand millimeters in a meter, and one thousand meters in a kilometer . All prefixes are multiples of 10, as you can see from the SI Prefixes Table . The prefixes are never combined; a millionth of a kilogram is a milligram not a microkilogram .
    ::可以在 SI 单位中添加一个前缀, 使原单位具有多个。 SI 前缀是一个名称或符号, 放在一个计量单位( 或其符号) 面前, 形成一个小数点或单位的多个。 例如, 千- 乘以千和毫- 乘以千分之倍数, 所以在一米中有一千毫米, 在一公里中有千米。 所有前缀都是十倍数, 正如您从 SI 前缀表格中看到的那样 。 前缀从不合并; 千分之百万是毫克, 不是微公斤 。

    Name Symbol Factor of 10
    tera- T 1,000,000,000,000 (10 12 ) trillion (thousand billion)
    giga- G 1,000,000,000 (10 9 ) billion (thousand million)
    mega- M 1,000,000 (10 6 ) million
    kilo- k 1000 (10 3 ) thousand
    hecto- h 100 (10 2 ) hundred
    deca- da 10 (10 1 ) ten
    deci- d 1 (10 -1 ) tenth
    centi- c 0.1 (10 -2 ) hundredth
    milli- m 0.01 (10 -3 ) thousandth
    micro- µ 0.00001 (10 -6 ) millionth
    nano- n 0.00000001 (10 -9 ) billionth
    pico- p 0.00000000001 (10 -12 ) trillionth

    Summary
    ::摘要

    • The measurements that scientists use are based on the International System of Units (SI), which is form of the metric system. Based on multiples of ten, it is the world's most widely used system of units, both in science and business.
      ::科学家使用的测量方法以国际单位体系为基础,该体系是衡量系统的形式,根据10倍的倍数,是全世界在科学和商业领域最广泛使用的单位体系。

    Review
    ::回顾

    1. What is SI?
      ::什么是职业妇协?
    2. Why is it important that scientists use common units of measurement?
      ::为什么科学家必须使用共同的计量单位?
    3. Which one of the following units of measurement would be the most appropriate in determining the mass of a banana? Kilograms, micrograms, or grams.
      ::在确定香蕉质量时,以下哪一种计量单位最为合适?
    4. What is the standard SI unit for measuring volume, weight, time, and length?
      ::衡量体积、重量、时间和长度的标准SI单位是什么?
    5. What is the shorthand unit for .000056 grams, 5,600,000,000 seconds, .56 liter, and 560 meter?
      ::0.0056克,5600万秒,5.56升和560米的速记单位是什么?