Which of the following is an example of how a scientist might use a model a. a stopwatch is used to time the rate of a chemical reaction. b. a microscope is used to magnify a group of cells on a slide. c. a wrench is used to tighten a nut on a piece of wood. d. the end of a slinky is moved vertically up and down to simulate a wave.

The correct answer will be option-D.

Explanation:

A scientific model is the simplified visual representation of the complex system which occurs in nature.

The scientific models used could be 2 dimensional or 3-dimensional representation of the phenomenon which plays an important role in the scientific world. The are used by the scientist to explain the phenomenon to the layman as well as by the researchers to prove the hypothesis.

In the given option, the best example of the scientific model will be the one which uses the up-down movement of the slinky which represents the movement of the waves as the travelling waves are invisible to humans.

Thus, option-D is the correct answer.

dynamic equilibrium is the answer.