Final answer:
A model is a representation of something that is difficult to directly display, used in relativity and quantum mechanics. It helps physicists analyze scenarios and perform calculations. A theory, on the other hand, is an explanation based on scientific evidence.
Step-by-step explanation:
A model is a representation of something that is often too difficult (or impossible) to display directly.
It is justified with experimental proof and is only accurate under limited situations.
In the context of relativity and quantum mechanics, models are particularly useful because they help physicists analyze scenarios and perform calculations, or represent situations in computer simulations.
For example, in the planetary model of the atom, electrons are pictured as orbiting the nucleus, similar to how planets orbit the Sun.
This mental image aids in understanding observations, such as the emission of light from hot gases.
A theory, on the other hand, is an explanation for patterns in nature that is supported by scientific evidence and verified multiple times.
While some theories include models to visualize phenomena, others do not require models because they can be directly observed with our senses, like Newton's theory of gravity.