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

I modelli sono rappresentazioni di fenomeni difficili da osservare direttamente. Ad esempio, la progressione dei modelli atomici può spiegare come sono messi insieme gli atomi e di cosa è fatta la materia.
Una teoria spiega i fenomeni naturali sulla base di osservazioni, esperimenti e principi fondamentali.
Ad esempio, Galileo lasciò cadere oggetti leggeri e pesanti da una torre. Da questo esperimento, propose una teoria secondo cui l'accelerazione di un corpo in caduta è indipendente dal suo peso. Tuttavia, il tasso di caduta di una piuma e di una palla da baseball non sono gli stessi, a meno che non vengano lasciati cadere nel vuoto per eliminare la resistenza dell'aria.
La previsione di Galileo corrisponde a un modello idealizzato che vale solo per gli oggetti con un peso molto maggiore della forza esercitata dall'aria.
Una legge scientifica è un'affermazione concisa che descrive il comportamento di qualsiasi fenomeno naturale. Una legge prevede ciò che accade, mentre una teoria propone il perché.
Ad esempio, una legge prevede quanto lontano viaggia una palla quando viene lanciata con una certa angolazione, mentre una teoria utilizza la gravità per spiegare la traiettoria parabolica della palla.

<ol>
	<li>Young, H.D. e Freedman, R.A. (2012). Fisica universitaria con fisica moderna. San Francisco, CA: Pearson; sezione 1.1-1.2; pagine 2–4.</li>
	<li>Giancoli, D.C. (2014). Fisica: Principi con applicazioni, Volume 1, 7a edizione, 1900 E. Lake Ave., Glenview, IL: Pearson Education, Inc.; sezione 1.3; pagina 5.</li>
</ol>

modelli, teorie, e leggi

Gli scienziati utilizzano frequentemente modelli per aiutarli a comprendere una specifica serie di fenomeni. In fisica, un modello è una versione condensata di un sistema fisico troppo complesso da studiare approfonditamente. Un esempio è il modello delle onde luminose; a differenza delle onde dell'acqua, le onde luminose sono tipicamente invisibili per noi. Tuttavia, è utile pensare alla luce come composta da onde, poiché le indagini mostrano che la luce si comporta come onde d'acqua. Poiché è impossibile vedere visivamente ciò che sta realmente accadendo, un modello funge da rappresentazione mentale o visiva approssimativa del fenomeno. Un modello assomiglia tipicamente strutturalmente al fenomeno in studio ed è relativamente semplice. Un modello utile conserva i componenti critici di un problema semplificandolo solo a sufficienza per renderlo praticabile.

Nel frattempo, una teoria è più completa, approfondita e in grado di fare previsioni precise che possono essere testate statisticamente. Il fenomeno in studio è definito una teoria per una prospettiva più ampia.

I fisici studiano le manifestazioni naturali e cercano collegamenti che le leghino. Quando questi schemi sono ben stabiliti e frequentemente applicati, vengono definiti leggi fisiche o principi. Determinate affermazioni succinte ma generali fatte dagli scienziati su come funziona la natura sono state classificate come leggi. L'affermazione di una legge assume spesso la forma di un'equazione o di una relazione tra due quantità. Ad esempio, la legge della conservazione delle cariche afferma che la carica elettrica netta di un sistema isolato rimane sempre conservata. La maggior parte delle volte, gli esperimenti supportano le affermazioni definite leggi su un ampio spettro di manifestazioni osservabili. Un'affermazione è chiamata "legge" quando la sua applicabilità è stata stabilita su un ampio spettro di situazioni, e qualsiasi restrizione e il campo di applicabilità sono ben compresi.

È cruciale distinguere tra un modello o una teoria e il sistema o le manifestazioni effettive. Le leggi scientifiche sono descrittive e hanno lo scopo di descrivere come si comporta la natura, non come dovrebbe comportarsi. Le leggi, come le teorie, non possono essere testate in ogni scenario.

Modelli, teorie, e leggi

Gli scienziati usano spesso modelli per aiutarli a comprendere una specifica collezione di fenomeni. In fisica, un modello è una versione condensata di un ...

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Education

Didattica

JoVE Core

Physics

Fisica

Unit 1

Unità 1

Units, Dimensions, and Measurements

Unità, dimensioni e misurazioni

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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 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.

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PS.1.f

PH.1

PH.1.d

PH.1.e

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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

BIO.1.G

BIO.1.H

BIO.3

BIO.3.A

PHYS.1

PHYS.1.A

PHYS.1.H

PHYS.2

PHYS.2.A

PHYS.3

PHYS.3.A

Chemistry and Physics

IPC.1

IPC.1.A

IPC.1.H

IPC.2

IPC.2.A

IPC.3

IPC.3.A

Scientific Method

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Hypothesis Test for Test of Independence

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Empirical Method to Interpret Standard Deviation

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Data Collection by Experiments

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Solving Problems in Physics

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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

A study design is a set of techniques that allow a researcher to collect and analyze data from different variables defined for a specific research ...

Observational Studies

Observational studies are a type of analytical study where researchers observe events without any interventions. In other words, the researcher does not ...

Experimental Designs

An experimental design is a systematic process that allows researchers to evaluate the relationship between dependent and independent variables. There are ...

Randomized Experiments

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Crossover Experiments

Crossover experiments, also called the repeated-measurements design, is a study design in which all experimental units are exposed to all treatments in ...

Controls in Experiments

When conducting an experiment, it is crucial to have control to reduce bias and accurately measure the dependent variables. It also marks the results more ...

Bias

Bias refers to any tendency that prevents a question from being considered unprejudiced. In research, bias occurs when one outcome or answer is selected ...

Blinding

Blinding is a commonly used method of not telling participants which treatment a subject is receiving. Blinding is a critical part of a randomized control ...

Clinical Trials

Clinical trials are prospective experimental studies conducted on humans to determine the safety and efficacy of treatments, drugs, diet methods, and ...

Data Collection by Observations

Data collection refers to a systematic way of obtaining, observing, measuring, and analyzing accurate information. Observational studies are one of the ...

Data Collection by Survey

The systematic method of obtaining and analyzing accurate information of a population is called data collection. A survey is a standard method of data ...

Units and Standards of Measurement

A physical quantity is defined either by specifying its measurement method or by stating how it is calculated from other measurements. For example, ...

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

A frequency is the number of times a value of the data occurs. The sum of all the frequency values represents the total number of students included in the ...

Ogive Graph

An ogive graph is sometimes called a cumulative frequency polygon. It is one type of frequency polygon that shows cumulative frequency. In other words, ...

Histogram

The histogram is a graphical representation in the x-y form of data distribution in a data set. The horizontal x-axis is labeled with what the data ...

Relative Frequency Histogram

The relative frequency depicts the proportion of data points that have each value. The frequency tells the number of data points that have each value. ...

Scatter Plot

The most common and easiest way to display the relationship between two variables, x and y, is a scatter plot. A scatter plot shows the direction of a ...

Time-Series Graph

A time-series graph is a line graph with repeated measurements taken at successive intervals of time. It is also called a time series chart. To construct ...

Bar Graph

A bar graph is also called a bar chart and consists of bars that are separated from each other. It either uses horizontal or vertical bars to show ...

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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