Name: si units and metric prefixes
Uploaded: 2023-09-22T11:49:19.000Z
Duration: 1 min 29 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.1.E.

International System of Units

国际单位制在全球范围内被广泛接受，其基本单位为米、千克和秒。这些单位是绝对的，其数值不会因地点不同而改变。
前缀用于表示更大或更小的量。毫（milli）、微（micro）和纳（nano）用于表示较小的量，而千（kilo）、兆（mega）和吉（giga）用于表示较大的量。
然而，在基本单位中，千克是唯一一个带有前缀的基本单位。
在表示单位和前缀时需要遵循一些规则。首先，使用点来区分组合单位中的各个单位。
其次，复合单位的分母中应避免使用前缀，前缀仅在复合单位的分子中表示。
第三，作用于带前缀单位的指数幂同时适用于该前缀及其单位，最后，结果应使用单一前缀表示。
与公制系统不同，国际单位制（SI）不使用“十”（deca）或“厘”（centi）作为倍数单位。

<ol>
	<li>希伯勒，RC（2016 年）。工程力学 \u2012 静力学和动力学。 新泽西州霍博肯:Pearson Prentice Hall。第 9\u201210 页</li>
	<li>比尔，F.P.;约翰斯顿，ER;马祖克，DF;克伦威尔，PJ 和塞尔夫，BP（2019 年）。工程师的矢量力学 \u2012 静力学和动力学。纽约:麦格劳-希尔。第 5 页和第 7 页</li>
	<li>梅里亚姆，JL;Kraige， LG 和 Bolton， JN （2020）。工程力学 \u2012 静力学。新泽西州霍博肯:约翰·威利。第 7 页和第 8 页</li>
</ol>

国际单位制

国际单位制（SI制度），是一种全球广泛接受和使用的度量制度。SI制度是基于三个绝对的基本单位，并且它们的值不会随着地点的改变而改变。这些基本的单位是米、千克和秒。 SI制度使用前缀来定义较大和较小的量。例如，使用毫、微和纳来定义较小的量，而千、兆和吉则用来表示较大的量。千克是SI制度基本单位中唯一带有前缀的单位。 在对单位和前缀进行表示时必须遵循几个规则。首先，使用点来将复合单位分隔开；其次，前缀仅出现在复合单位的分子中，而不会出现在分母中。第三，带有前缀单位的指数幂可以应用于前缀及单位中；最后，结果应使用一个前缀表示。 需要注意的是，与公制不同，SI制度不会使用到十的倍数或百分数。SI制度的前缀是基于十的幂次来进行计量的，因此这些基本单位没有前缀。SI单位旨在利用单位制度来简化和标准化科学测量。 SI制度之所以被全球使用的主要原因是其在测量过程中的准确性和精度。即使是最微小和最庞大的量，也可以使用基本单位和前缀来进行精确量化。 SI制度中，长度的基本单位是米，米被定义为光在真空中并且在特定的时间内行进的距离。其他长度的测量，如厘米、千米和毫米，则可以通过使用前缀系统从米导出。 SI制度的基本质量单位是千克，千克能够被定义为一组国际千克原型中基础物体的质量。对于其他质量的测量，例如克和毫克，则可以通过使用前缀系统从千克导出。 SI制度的时间基本单位是秒，被定义为铯-133原子能级间的特定跃迁中伴随辐射的循环次数，即9,192,631,770次，所用的时间。从秒开始，便可以使用前缀系统导出其他时间单位，例如分钟和小时。 除了这些单位，还定义了其他的四个单位作为基本的度量单位。它们分别是安培、开尔文、摩尔和坎德拉。

国际单位制（SI）是全球公认并广泛使用的通用测量系统。SI 系统是……

Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

An Introduction to Statics

静力学导论

KEY TERMS AND CONCEPTS

关键术语与概念

si units and metric prefixes

SI units and metric prefixes provide a standard way to measure size, mass, and time. The International System of Units, or SI system, is used worldwide because it gives scientists a common language for measurement. Its values do not change with location, which helps keep results consistent.

The SI system is built on three base units: meter, kilogram, and second. These are the core units for length, mass, and time. The kilogram is the only base unit that already includes a prefix.

Prefixes make it easy to express very large or very small values. Milli, micro, and nano represent smaller quantities. Kilo, mega, and giga represent larger quantities. SI prefixes are based on powers of ten, and the base unit has no prefix.

Several rules apply when writing SI units. Dots are used to separate units in composite units. A prefix should not appear in the denominator, only in the numerator. If a unit with a prefix is raised to a power, the power applies to both the prefix and the unit. The final answer should use just one prefix. Unlike the metric system, SI does not use deca or centi.

SI units help simplify and standardize scientific measurements. They also improve accuracy and precision, even for very small or very large quantities. The meter is defined as the distance light travels in a vacuum during a specific time frame. Other length units, such as centimeter, kilometer, and millimeter, come from the meter.

The kilogram is the SI base unit of mass. It was defined as the mass of a set of foundational objects called the International Prototype of the Kilogram. Grams and milligrams are derived from the kilogram. The second is the SI base unit of time and is defined by 9,192,631,770 cycles of radiation from a specific transition in cesium-133. Minutes and hours can be derived from the second. Four more fundamental units are also part of SI: ampere, Kelvin, mole, and candela.

SI Units and Metric Prefixes

an introduction to mechanics

Mechanics in Physics and Engineering

Mechanics is a key branch of physics that explains how objects stay at rest or move when forces act on them. It also has major uses in engineering and science. The topic helps students understand everyday motion, machine behavior, and the way many systems work. The recorded history of mechanics begins with Aristotle, who lived from 384 to 322 BC. He linked mechanics with physical theory and looked for a broad universal explanation. Later, Newton defined mechanics as the study of objects at...

basic concept

Fundamental Quantities in Engineering Mechanics

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newton's law of motion

Newton's Laws and Everyday Motion

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newton's law of gravitational attraction

Gravity Between Masses and Distance

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units of measurement

SI and Customary Measurement Systems

Mechanical engineering depends on units of measurement for precise and accurate calculations. These units give engineers a standard way to express and compare physical quantities. They are essential when designing and analyzing machines and mechanical systems. Many historical measurement systems have been used over time. Examples include the Babylonian system, the Roman system, the Egyptian system, the Olympian system, the British system, and the Indus Valley system. Today, the International...

international system of units

SI units and metric prefixes provide a standard way to measure size, mass, and time. The International System of Units, or SI system, is used worldwide because it gives scientists a common language for measurement. Its values do not change with location, which helps keep results consistent. The SI system is built on three base units: meter, kilogram, and second. These are the core units for length, mass, and time. The kilogram is the only base unit that already includes a prefix. Prefixes...

numerical calculations

Engineering Notation and Significant Figures

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accuracy, limits, and approximation

Accuracy and Approximation in Calculations

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dimensional analysis

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key terms and concepts

Learn how SI units use meters, kilograms, seconds, and metric prefixes to measure length, mass, and time with accuracy and consistency.

SI Units and Metric Prefixes | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Physics

PHYS.1

PHYS.1.E

Chemistry and Physics

IPC.1

IPC.1.E

The Scientific Method

The scientific method is a detailed, empirical problem-solving process used by biologists and other scientists. This iterative approach involves ...

Inductive Reasoning

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Deductive Reasoning

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Correlation and Causation

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Ask questions and define problems related to specialized topics of study based on observations or information from text, phenomena, models, or investigations;

112.51.c.1.A.

Scientific Method

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Demonstrating the Scientific Method with Tree Branches
ExpandObtain branches containing a few dozen typical leaves from five different local tree species. ...

Observation and Background Research
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Problem-Solving

A problem-solving strategy is a plan of action used to find a solution. It involves trial and error, algorithms, heuristics, and insights. Effective ...

Problem Definition

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Apply science practices related to specialized topics of study to plan and conduct investigations or use engineering practices to design solutions to problems;

112.51.c.1.B.

Proper Personal Protective Equipment

Robert M. Rioux &#38; William A Elliott, Pennsylvania State University, University Park, PA
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Emergency Eyewash and Shower Stations

Robert M. Rioux, Pennsylvania State University, University Park, PA
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Electrical Safety

Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
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Working with Centrifuges

Source: Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
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Working with Hot and Cold Sources

Source: Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
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guidelines-in-case-of-a-laboratory-emergency

Guidelines in Case of a Laboratory Emergency

Robert M. Rioux &amp; Zhifeng Chen, Pennsylvania State University, University Park, PA
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Chemical Storage: Categories, Hazards And Compatibilities

Source: Robert M. Rioux &amp; Taslima A. Zaman, Pennsylvania State University, University Park, PA
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Safe Handling of Mineral Acids

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Handling Chemical Spills

Source: Robert M. Rioux &#38; Taslima Zaman, Pennsylvania State University, University Park, PA
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Proper Use of Autoclaves

Robert M. Rioux &amp; Zhifeng Chen, Pennsylvania State University, University Park, PA
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Fume Hoods and Laminar Flow Cabinets

Robert M. Rioux &amp; William A. Elliott, Pennsylvania State University, University Park, PA
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Decontamination for Laboratory Biosafety

Robert M. Rioux and Zhifeng Chen, Pennsylvania State University, University Park, PA
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Proper Waste Disposal

Robert M. Rioux and Taslima A. Zaman, Pennsylvania State University, Pennsylvania, PA

Users are responsible for the proper disposal of the waste ...

Use appropriate safety equipment and practices during laboratory, classroom, and field investigations as outlined in Texas Education Agency-approved safety standards;

112.51.c.1.C.

Common Lab Glassware and Uses

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
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Lab Techniques

Measurement Accuracy
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	Preparation of LaboratoryExpand
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	Determining the Density of an EggExpand
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Proper Lab Notebook Keeping

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Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

	Preparation of the LaboratoryExpand
	Here, we show the laboratory preparation ...

Source: Lara Al Hariri and Ahmed Basabrain at the University of Massachusetts Amherst, MA, USA

	Nitration of Methyl BenzoateExpand
	From this lab onward, ...

Use tools appropriate to the specialized topic of study;

112.51.c.1.D.

SI Units: 2019 Redefinition

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The International System of Units, known as the SI system, is a universally accepted measurement system recognized and used worldwide. The SI system is ...

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Collect quantitative data using the International System of Units (SI) or qualitative data as evidence as appropriate to the specialized topic of study;

Review and Preview

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Ogive Graph

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Histogram

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Relative Frequency Histogram

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Scatter Plot

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Time-Series Graph

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Bar Graph

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Multiple Bar Graph

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Pareto Chart

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Pie Chart

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Organize quantitative or qualitative data using representations appropriate to the specialized topic of study such as scatter plots, line graphs, bar graphs, charts, data tables, diagrams, scientific drawings, and student-prepared models;

112.51.c.1.F.

Modeling and Similitude

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...

design-example-creating-a-hydraulic-model-of-a-dam-spillway

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/files/media/science-education/science-education-thumbs/14686.jpg

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112.51.c.1.G.

Scientific Laws and Theories

Scientific Laws

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Distinguish among scientific hypotheses, theories, and laws as appropriate to the specialized topic of study.

112.51.c.1.H.

Identify advantages and limitations of models such as their size, scale, properties, and materials as appropriate to the specialized topic of study;

112.51.c.2.A.

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types-of-errors-detection-and-minimization

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Analyze data appropriate to the specialized topic of study by identifying significant statistical features, patterns, sources of error, and limitations;

112.51.c.2.B.

Scientific and engineering practices. The student, for at least 40% of instructional time, asks questions, identifies problems, and plans and safely conducts classroom, laboratory, and field investigations to explain phenomena or design solutions using appropriate tools and models. The student is expected to:

SI Units and Metric Prefixes

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