Name: si base units behind measured quantities
Uploaded: 2023-04-30T10:47:58.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Physical Science

PS.1

PS.1.b

Base Quantities and Derived Quantities

Wielkości fizyczne można podzielić na wielkości bazowe i wielkości pochodne. Wielkości bazowe mogą być wyrażone w procesie pomiaru, a ich jednostki są znane jako jednostki podstawowe.
Na przykład odległość między dwoma punktami jest mierzona w metrach. Tutaj wielkością bazową jest odległość, a jednostką używaną do jej pomiaru jest metr, który jest jednostką podstawową.
Wielkości fizyczne uzyskane z kombinacji wielkości bazowych są znane jako wielkości pochodne, a jednostki używane do definiowania tych wielkości są znane jako jednostki pochodne.
Na przykład prędkość poruszającego się samochodu z jednego punktu do drugiego jest definiowana jako przebyta odległość podzielona przez czas podróży. W tym przypadku prędkość jest wielkością pochodną uzyskaną z wielkości bazowych, odległości i czasu.
Jednostką prędkości są metry na sekundę, jednostka pochodna od jednostek podstawowych, metrów i sekund. Wszystkie wielkości pochodne i jednostki pochodne są definiowane odpowiednio na podstawie wielkości bazowych i jednostek podstawowych.

ilości bazowe i ilości pochodne

W każdym systemie jednostek, jednostki niektórych wielkości fizycznych muszą być określone w procesie pomiarowym. Miary te są wielkościami podstawowymi układu, a ich jednostki są jednostkami podstawowymi układu. Algebraiczne kombinacje wartości podstawowych można następnie wykorzystać do wyrażenia wszystkich innych wielkości fizycznych. Każdą z tych wielkości fizycznych określa się następnie jako wielkość pochodną, ​​a każdą jednostkę jako jednostkę pochodną.

Międzynarodowa Organizacja Normalizacyjna zaleca stosowanie siedmiu wielkości podstawowych, które tworzą Międzynarodowy System Ilości (ISQ). Wszystkie pozostałe wielkości fizyczne można wyrazić jako kombinacje tych siedmiu podstawowych wielkości fizycznych. Na przykład w geometrii pojęcie pola jest zawsze obliczane jako iloczyn dwóch długości. Zatem powierzchnia jest wielkością pochodną, ​​którą można wyrazić w jednostkach podstawowych SI za pomocą metrów kwadratowych. Tymczasem gęstość definiuje się jako masę podzieloną przez objętość, którą wyraża się w kilogramach na metr sześcienny (kg/m3) w podstawowych jednostkach SI. Podsumowując, wszystkie wielkości fizyczne można wyprowadzić z siedmiu wielkości podstawowych, a jednostki wszystkich wielkości fizycznych można wyprowadzić z siedmiu jednostek podstawowych układu SI.

Ten tekst jest adaptacją <a href="https://openstax.org/books/university-physics-volume-1/pages/1-2-units-and-standards">Openstax University Physics, tom 1, sekcja 1.2 Jednostki i standardy. </a>

Ilości bazowe i ilości pochodne

W każdym układzie jednostek miar jednostki dla niektórych wielkości fizycznych muszą być określone w procesie pomiaru. Pomiary te są wielkościami bazowymi ...

Education

JoVE Core

Physics

Fizyka

Unit 1

Jednostka 1

Units, Dimensions, and Measurements

Jednostki, wymiary i pomiary

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

si base units behind measured quantities

SI base units are the starting point for measuring physical quantities. In any system of units, some quantities must be defined through direct measurement. These are called base quantities, and their units are base units.

Other physical quantities are built from these base values by algebraic combinations. These are called derived quantities, and their units are derived units. For example, area comes from two lengths multiplied together. It is a derived quantity and is written in SI base units as square meters.

The International Organization for Standardization recommends seven base quantities. Together, they make up the International System of Quantities, or ISQ. Every other physical quantity can be expressed as a combination of these seven base physical quantities. Density is one example. It is mass divided by volume and is written in SI base units as kilograms per cubic meter, or kg/m^3.

In this way, the seven SI base units provide the foundation for every other unit. Once the base quantities are known, derived quantities and derived units can be written from them. This idea helps connect common measurements like area and density to the full SI system.

SI Base Units Behind Measured Quantities

the scope of physics

How Physics Shapes Science and Technology

Physics studies the interactions of energy, matter, space, and time. It looks for the basic mechanisms that explain natural phenomena. The word physics comes from the Greek word physis, which means nature. Physics helps us understand the natural world at its most fundamental level. It relies on quantitative laws, or rules written in numbers and measurements, to describe how things behave. That approach can also help other fields improve the limits of current technology. Physics matters in...

orders of magnitude

Estimating Scale with Powers of 10

Orders of magnitude help estimate the scale of a number using powers of 10. It is a simple way to round values to the nearest power of 10. This makes it easier to compare very large and very small numbers. To find the order of magnitude of a number, take its base-10 logarithm and round to the nearest integer. The result gives the power of 10 that most closely matches the original value. This method gives a consistent estimate of size without using exact digits. Orders of magnitude are useful...

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models, theories, and laws

Scientific Models, Theories, and Laws

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units and standards of measurement

SI Units for Physical Quantities

SI units give a standard way to measure physical quantities. A physical quantity can be defined by how it is measured or by how it is calculated from other measurements. For example, the mass and dimensions of a metallic cube can be found with a weighing machine and a meter scale. Some quantities are built from others. The volume of a cube is the cube of its side length. The density of the cube is then found by dividing mass by volume. Measurements are written in units, which are standardized...

estimation of the physical quantities

Fermi Estimation for Physical Quantities

Fermi estimation helps physicists, scientists, and engineers make rough calculations for physical quantities. These estimates are also called guesstimates, order-of-magnitude approximations, back-of-the-envelope calculations, or Fermi calculations. Enrico Fermi was known for making these kinds of estimates with surprising precision. Estimation is not random guessing. It uses prior experience and sound physical reasoning to get a rough value for a quantity. This kind of reasoning helps build...

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base quantities and derived quantities

SI base units are the starting point for measuring physical quantities. In any system of units, some quantities must be defined through direct measurement. These are called base quantities, and their units are base units. Other physical quantities are built from these base values by algebraic combinations. These are called derived quantities, and their units are derived units. For example, area comes from two lengths multiplied together. It is a derived quantity and is written in SI base units...

conversion of units

Unit Conversion Steps and Real-World Errors

Unit conversion lets you change a measurement from one unit to another. It is useful in everyday life, such as when a cookbook gives amounts in liters or ounces and you need cups instead. It also helps when directions use feet or meters, but you want to know the distance in miles. The first step is to list the given unit and the unit you need. The second step is to choose a conversion factor, which is a ratio that shows how many of one unit equal another unit. For example, 1,000 meters equal 1...

accuracy and precision

Repeated Measurements in Science

Repeated measurements help scientists check the quality of their results. They are used to judge both precision and accuracy. These two ideas are related, but they do not mean the same thing. Measurements are precise when repeated trials give very similar results. Precision shows how closely the values agree with one another. Measurements are accurate when the result is very close to the true value or the accepted value. Accuracy shows how closely the values agree with the real target. High...

random and systematic errors

How Measurement Errors Affect Results

Measurement errors can change how accurate and precise a result appears. Scientists try to record measurements as carefully as possible, but errors can still happen. These errors are usually random or systematic. Random errors come from inconsistency or fluctuation in the measuring process. They can also come from changes in the quantity being measured. In repeated measurements, random error may make a value appear greater than the true value one time and less than it the next. A simple...

rules for significant figures

Measurement Precision and Significant Figures

Measurement precision depends on the tool used, and significant figures show that precision. A ruler can measure length to the closest millimeter. A caliper can measure length to the nearest 0.01 mm, so it gives a more precise measurement because it can detect very small changes in length. When a value is written from a measurement, the last digit is not exact. The person making the measurement must estimate that digit. For example, a stick that seems to fall between 13.2 cm and 13.3 cm must...

significant figures in calculations

Rounding Rules for Significant Figures

Rounding rules for significant figures help show the right level of certainty in measured results. When a calculation is reported with the correct number of significant figures, it better matches the uncertainty in the measurements. The rounding rule depends on the type of math being done. For addition and subtraction, the result should have the same number of decimal places as the number with the fewest decimal places. For multiplication and division, the result should have the same number of...

dimensional analysis

Dimensional Checks in Physics Equations

Dimensional consistency is a key check in physics equations. It means the dimensions on both sides of an equation must match. The idea helps show whether an equation can represent a real physical law. The first rule is simple: expressions on each side of the equal sign must have the same dimensions. That makes sense because you can only add or subtract quantities of the same type. The second rule says that the input to a standard mathematical function, such as a trigonometric function, a...

problem solving: dimensional analysis

Dimensional Checks for Physics Equations

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solving problems in physics

Physics Problem Solving: Strategy to Check

Physics problem solving uses general physical principles to work out specific situations. It is a key skill in physics, and it can also help with everyday life. The same analytical skills can be used in new situations, while a list of facts can never cover every possible case. Solving physics problems also takes creativity and insight. These skills grow with experience and practice. There is no simple step-by-step method that works for every problem, but a three-stage process can guide the...

key terms and concepts

Learn how base quantities, base units, derived quantities, and derived units connect in the SI system, with examples like area and density.

SI Base Units Behind Measured Quantities | JoVE K12

physics

JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

PH.1

PH.1.b

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.1

CHEM.1.E

PHYS.1

PHYS.1.E

Chemistry and Physics

IPC.1

IPC.1.E

Scientific Method

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empirical-method-to-interpret-standard-deviation

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The student will demonstrate an understanding of scientific and engineering practices by asking questions and defining problems
• ask questions that require empirical evidence to answer
• develop hypotheses indicating relationships between independent and dependent variables
• offer simple solutions to design problems

PS.1.a

What is an Experiment?

An experiment is a planned activity carried out under controlled conditions. The purpose of an experiment is to investigate the relationship between two ...

Study Design in Statistics

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Observational Studies

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Experimental Designs

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Randomized Experiments

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Crossover Experiments

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Controls in Experiments

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Blinding

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Clinical Trials

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Data Collection by Observations

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Units and Standards of Measurement

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Estimation of the Physical Quantities

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In any system of units, the units for some physical quantities must be specified through a measurement process. These measurements are the base quantities ...

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Sometimes, there is a need to convert from one unit to another one. For instance, reading a cookbook in which quantities are expressed in units of liters ...

The student will demonstrate an understanding of scientific and engineering practices by planning and carrying out investigations
• independently and collaboratively plan and conduct observational and experimental investigations; identify variables, constants, and controls where appropriate and include the safe use of chemicals and equipment
• evaluate the accuracy of various methods for collecting data
• take metric measurements using appropriate tools and technologies
• apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process or system

Review and Preview

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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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What is Variation?

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Range

The range is one of the measures of variation. It can be defined as the difference between a dataset&#39;s highest and lowest values. For example, in the ...

Standard Deviation

The most commonly used measure of variation is the standard deviation. It is a numerical value measuring how far data values are from their mean. The ...

Calculating Standard Deviation

The standard deviation is the most common measure of variation. It is a value that tells us how far a data value is from the mean value in a dataset. ...

Variance

&#160;The deviations show how spread out the data are about the mean. A positive deviation occurs when the data value exceeds the mean, whereas a negative ...

Coefficient of Variation

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Contingency Table

A contingency table provides a way of portraying data that can facilitate calculating probabilities. It is a method of displaying a frequency distribution ...

Statistical Analysis: Overview

An analysis is usually conducted by replicated sampling or repeated measurements on the same sample. This leads to scattered results rather than a single ...

The student will demonstrate an understanding of scientific and engineering practices by pnterpreting, analyzing, and evaluating data
• construct and interpret data tables showing independent and dependent variables, repeated trials, and means
• construct, analyze, and interpret graphical displays of data and consider limitations of data analysis
• apply mathematical concepts and processes to scientific questions
• use data to evaluate and refine design solutions to best meet criteria

PS.1.c

Models, Theories, and Laws

Scientists frequently use models to help them comprehend a specific collection of phenomena. In physics, a model is a condensed version of a physical ...

Inductive Reasoning

Inductive reasoning is a form of logical thinking that uses related observations to arrive at a general conclusion. It is uncertain and operates in ...

Deductive Reasoning

Deductive reasoning, or deduction, is the type of logic used in hypothesis-based science. In deductive reasoning, the pattern of thinking moves in the ...

The student will demonstrate an understanding of scientific and engineering practices by constructing and critiquing conclusions and explanations
• construct scientific explanations based on valid and reliable evidence obtained from sources (including the students' own investigations)
• construct arguments supported by empirical evidence and scientific reasoning
• generate and compare multiple solutions to problems based on how well they meet the criteria and constraints
• differentiate between a scientific hypothesis, theory, and law

PS.1.d

The student will demonstrate an understanding of scientific and engineering practices by developing and using models
• construct, develop, and use models and simulations to illustrate and/or explain observable and unobservable phenomena
• evaluate limitations of models

PS.1.e

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

The student will demonstrate an understanding of scientific and engineering practices by obtaining, evaluating, and communicating information
• read scientific texts, including those adapted for classroom use, to determine the central idea and/or obtain scientific and/or technical information
• gather, read, and synthesize information from multiple appropriate sources and assess the credibility, accuracy, and possible bias of each publication
• construct, use, and/or present an oral and written argument supported by empirical evidence and scientific reasoning

PS.1.f

SI Base Units Behind Measured Quantities

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