What does variable mean in science?

In this experiment, you will use a track, a toy car, and some washers to explore newton’s first two laws of motion. you will make observations and collect data regarding the motion of these objects. in the space below, write a general scientific question that you will answer by doing this experiment.

An observer that stands still as the electron moves by him, will observe

Protons and neutrons are found within the nucleus of an atom