# Models, Theories, and Laws

JoVE Core
Physik
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JoVE Core Physik
Models, Theories, and Laws

### Nächstes Video1.4: Units and Standards of Measurement

Models are representations of phenomena that are difficult to observe directly. For example, the progression of atomic models can explain how atoms are put together and what matter is made of.

A theory explains natural phenomena based on observations, experiments, and fundamental principles.

For example, Galileo dropped light and heavy objects from a tower. From this experiment, he proposed a theory that a falling body's acceleration is independent of its weight. However, the rate of fall of a feather and a baseball are not the same, unless they are dropped in a vacuum to eliminate air resistance.

Galileo's prediction corresponds to an idealized model that applies only to objects with a weight much greater than the force exerted by the air.

A scientific law is a concise statement describing the behavior of any natural phenomenon. A law predicts what happens, while a theory proposes why.

For example, a law predicts how far a ball travels when launched at a certain angle, while a theory uses gravity to explain the parabolic trajectory of the ball.

## 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 system that is too complex to study thoroughly. One such example is the light wave model; unlike water waves, light waves are typically invisible to us. Nonetheless, it is helpful to think of light as being composed of waves, since investigations show that light behaves like water waves. Since it is impossible to visually see what is genuinely happening, a model serves as a rough mental or visual representation of the phenomenon. A model typically resembles the phenomenon being investigated structurally and is relatively simple. A helpful model preserves an issue's critical components while simplifying it just enough to make it workable.

Meanwhile, a theory is more comprehensive, in-depth, and capable of making precise predictions that can be tested statistically. The phenomenon being studied is referred to as a theory for a broader perspective.

Physicists study natural occurrences and look for connections linking them. When these patterns are well-established and frequently applied, they are referred to as physical laws or principles. Certain succinct but general comments made by scientists about how nature functions have been classified as laws. The statement of a law frequently takes the form of an equation or relationship between two quantities. For example, the law of conservation of charges states that the net electric charge of an isolated system always remains conserved. Most of the time, experiments support the statements referred to as laws across a broad spectrum of observable occurrences. A statement is called a "law" when its applicability has been established across a broad spectrum of situations, and any restrictions and the range of the applicability are well understood.

It is crucial to distinguish between a model or a theory and the actual system or occurrences. Scientific laws are descriptive and intended to describe how nature behaves, not how it ought to behave. Laws, like theories, cannot be tested in every scenario.