Name: scientific models, theories, and laws
Uploaded: 2023-05-16T08:18:40.000Z
Duration: 1 min 16 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Physical Science

PS.1

PS.1.d

Models, Theories, and Laws

Les modèles sont des représentations de phénomènes difficiles à observer directement. Par exemple, la progression des modèles atomiques peut expliquer comment les atomes sont assemblés et de quelle matière est faite.
Une théorie explique les phénomènes naturels sur la base d’observations, d’expériences et de principes fondamentaux.
Par exemple, Galilée a lâché des objets légers et lourds d’une tour. À partir de cette expérience, il a proposé une théorie selon laquelle l'accélération d'un corps en chute libre est indépendante de son poids. Cependant, le taux de chute d’une plume et d’une balle de baseball n’est pas le même, à moins qu’ils ne soient lâchés dans le vide pour éliminer la résistance de l’air.
La prédiction de Galilée correspond à un modèle idéalisé qui ne s'applique qu'aux objets ayant un poids bien supérieur à la force exercée par l'air.
Une loi scientifique est une déclaration concise décrivant le comportement de tout phénomène naturel. Une loi prédit ce qui se passe, tandis qu’une théorie propose pourquoi.
Par exemple, une loi prédit la distance parcourue par une balle lorsqu’elle est lancée à un certain angle, tandis qu’une théorie utilise la gravité pour expliquer la trajectoire parabolique de la balle.

<ol>
	<li>Young, H.D. et Freedman, R.A. (2012). La physique universitaire avec la physique moderne. San Francisco, Californie : Pearson ; sections 1.1 et 1.2 ; Pages 2 à 4.</li>
	<li>Giancoli, D.C. (2014). Physique : principes avec applications, volume 1, 7e édition, 1900 E. Lake Ave., Glenview, IL : Pearson Education, Inc. ; section 1.3 ; page 5.</li>
</ol>

modèles, théories et lois

Les scientifiques utilisent fréquemment des modèles pour les aider à comprendre une collection spécifique de phénomènes. En physique, un modèle est une version condensée d'un système physique trop complexe pour être étudié en profondeur. Un exemple en est le modèle des ondes lumineuses ; contrairement aux vagues d'eau, les ondes lumineuses sont généralement invisibles pour nous. Néanmoins, il est utile de penser à la lumière comme étant composée d'ondes, car les investigations montrent que la lumière se comporte comme des vagues d'eau. Comme il est impossible de voir visuellement ce qui se passe réellement, un modèle sert de représentation mentale ou visuelle approximative du phénomène. Un modèle ressemble généralement structurellement au phénomène étudié et est relativement simple. Un modèle utile préserve les composants critiques d'un problème tout en le simplifiant suffisamment pour le rendre exploitable.

En revanche, une théorie est plus complète, approfondie et capable de faire des prédictions précises qui peuvent être testées statistiquement. Le phénomène étudié est appelé une théorie dans une perspective plus large.

Les physiciens étudient les occurrences naturelles et recherchent des liens les reliant. Lorsque ces modèles sont bien établis et largement appliqués, ils sont appelés des lois physiques ou des principes. Certains commentaires concis mais généraux faits par les scientifiques sur le fonctionnement de la nature ont été classés comme des lois. L'énoncé d'une loi prend souvent la forme d'une équation ou d'une relation entre deux grandeurs. Par exemple, la loi de conservation des charges déclare que la charge électrique nette d'un système isolé reste toujours conservée. La plupart du temps, les expériences corroborent les énoncés appelés lois dans une large gamme d'occurrences observables. Un énoncé est appelé une "loi" lorsque son applicabilité a été établie dans une large gamme de situations, et que les restrictions et la portée de l'applicabilité sont bien comprises.

Il est crucial de faire la distinction entre un modèle ou une théorie et le système réel ou les occurrences. Les lois scientifiques sont descriptives et sont destinées à décrire comment la nature se comporte, et non pas comment elle devrait se comporter. Les lois, comme les théories, ne peuvent pas être testées dans toutes les situations.

Modèles, théories et lois

Les scientifiques utilisent fréquemment des modèles pour les aider à comprendre un ensemble spécifique de phénomènes. En physique, un modèle est une version condensée d’un ...

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Education

Enseignement

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Physics

Physique

Unit 1

Unité 1

Units, Dimensions, and Measurements

Unités, dimensions et mesures

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

scientific models, theories, and laws

Scientific models, theories, and laws help physicists describe natural phenomena. A model is a simplified version of a physical system that is too complex to study in full. It acts as a rough mental or visual picture of what may be happening. Good models keep the important parts and simplify the rest so the problem becomes workable.

The light wave model is one example. Light waves are usually invisible, so they cannot be seen in the same way as water waves. Even so, it is useful to think of light as waves because experiments show that light behaves like water waves. A model should resemble the phenomenon in a structural way, but it is not the same thing as the real system.

A theory goes further than a model. It is more complete, more detailed, and can make precise predictions that can be tested statistically. Physicists use theories to study natural events and the connections between them. The phenomenon being studied is viewed in a broader way when it is described as a theory.

When patterns are well established and used often, they are called physical laws or principles. A law is a short but general statement about how nature behaves. It often appears as an equation or a relationship between two quantities. For example, the law of conservation of charge says that the net electric charge of an isolated system remains conserved.

Experiments usually support laws across a wide range of observable situations. A statement is called a law when its range of use is known and its limits are understood. It is important to separate a model, theory, or law from the actual system or event it describes. Scientific laws are descriptive, so they explain how nature behaves, not how it should behave. Like theories, laws cannot be tested in every possible case.

Scientific Models, Theories, and Laws

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 help physicists describe natural phenomena. A model is a simplified version of a physical system that is too complex to study in full. It acts as a rough mental or visual picture of what may be happening. Good models keep the important parts and simplify the rest so the problem becomes workable. The light wave model is one example. Light waves are usually invisible, so they cannot be seen in the same way as water waves. Even so, it is useful to think of...

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 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...

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

Dimensional analysis helps check whether physics equations make sense. It compares the dimensions on each side of an equation and shows whether the units are consistent. This method is useful for spotting algebra errors, typos, and for remembering physical laws. A valid equation must follow two rules. First, both sides of an equality must have the same dimension, so only quantities with matching dimensions can be added or subtracted. Second, common math functions such as exponential,...

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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 scientific models simplify complex systems, how theories make testable predictions, and how laws describe patterns in nature across many situations.

Scientific Models, Theories, and Laws | JoVE K12

physics

JoVE Core Physique présente plusieurs branches de la physique fondamentale grâce à des vidéos animées concises et faciles à comprendre ; cela inclut: la cinématique, la dynamique, la mécanique des fluides, la mécanique statique, les ondes et l'acoustique. En parallèle, les vidéos de scientifiques à l'action démontrent l'application de concepts associés à ces domaines dans des expériences de recherche classiques et originales réalisées dans des laboratoires modernes du monde entier.

PS.1.e

PS.1.f

PH.1

PH.1.d

PH.1.e

PH.1.f

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.1.G.

112.51.c.1.H.

Alabama Course of Study Science

9-12

Earth and Space Science

Earth's Place in the Universe

9-12.ESS.1.3

112.51.c.3.

112.51.c.3.A.

Florida Department of Education

Nature of Science

SC.912.N.2

SC.912.N.2.2

SC.912.N.3

SC.912.N.3.2

SC.912.N.3.4

SC.912.N.3.5

Biology

BIO.1

BIO.1.A

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BIO.3

BIO.3.A

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PHYS.1.A

PHYS.1.H

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PHYS.2.A

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PHYS.3.A

Chemistry and Physics

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IPC.2.A

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IPC.3.A

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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?

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Study Design in Statistics

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Observational Studies

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Experimental Designs

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Controls in Experiments

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Bias

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Blinding

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Data Collection by Observations

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Data Collection by Survey

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Units and Standards of Measurement

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Estimation of the Physical Quantities

On many occasions, physicists, other scientists, and engineers need to make estimates of a particular quantity. These are sometimes referred to as ...

Base Quantities and Derived Quantities

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

Conversion of Units

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

PS.1.b

Review and Preview

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What is a Frequency Distribution

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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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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

Scientific Models, Theories, and Laws

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