1.3
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…
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.
View the full transcript and gain access to JoVE Core videos
Q1: What is the difference between a scientific model and a theory?
A model is a simplified representation of a complex physical system that preserves critical components while remaining workable. A theory is more comprehensive and in-depth, explaining natural phenomena based on observations and experiments. For example, the light wave model helps us understand light behavior by comparing it to water waves, while a theory explains why light behaves this way using fundamental principles.
Q2: How do scientific laws differ from theories in physics?
A law is a concise statement describing natural phenomena behavior and predicts what happens, while a theory proposes why it happens. Laws are often expressed as equations or relationships between quantities and apply across broad spectra of observable occurrences. For instance, a law predicts how far a ball travels when launched at a certain angle, while a theory uses gravity to explain the parabolic trajectory.
Q3: Why do scientists use models to study physical phenomena?
Models serve as rough mental or visual representations of phenomena too complex to study directly. Since many phenomena like light waves are invisible, models help scientists comprehend specific collections of phenomena by simplifying them structurally. A helpful model preserves an issue's critical components while making it workable enough for investigation and testing.
Q4: What does it mean when a statement is classified as a scientific law?
A statement is called a law when its applicability has been established across a broad spectrum of situations and any restrictions and range of applicability are well understood. Laws are descriptive statements intended to describe how nature behaves, not how it ought to behave. Most experiments support laws across many observable occurrences, such as the law of conservation of charge in isolated systems.
Q5: Can Galileo's falling body theory be applied to all objects?
Galileo's theory that falling body acceleration is independent of weight applies only to an idealized model for objects with weight much greater than air resistance forces. A feather and baseball fall at different rates in air but the same rate in a vacuum. This demonstrates that theories correspond to idealized models with specific conditions and limitations rather than universal applicability.
Q6: How are models used to represent invisible physical phenomena?
Models provide visual or mental representations of invisible phenomena by drawing structural similarities to observable systems. For example, light waves are typically invisible, but thinking of light as composed of waves helps scientists understand its behavior since investigations show light behaves like water waves. Models make the workable and testable what cannot be directly observed.
Q7: What is the relationship between observations, experiments, and scientific theories?
A theory explains natural phenomena based on observations, experiments, and fundamental principles. Scientists study natural occurrences and look for connections linking them; when these patterns are well-established and frequently applied, they become recognized as physical laws or principles. Theories enable precise predictions that can be tested statistically across various scenarios.