Final answer:
The motion diagram in the question represents the motion of a galloping horse along a straight path. It is related to the study of motion and mechanics in Physics.
Step-by-step explanation:
The subject of this question is Physics.
The motion diagram described in the question is a visual representation of the motion of a horse galloping along a straight path. The diagram consists of equally spaced dots that depict the horse's consecutive positions at different instants of time.
In this particular example, the motion diagram is related to the study of motion and mechanics in Physics. It can be used to analyze the horse's speed, acceleration, and displacement over time.