Final Answer:
The motion diagram depicting constant speed is likely the dust particle settling to the floor, the one with uniform acceleration is indicative of a ball dropped from the roof of a building, and the diagram showing decreasing acceleration suggests a descending rocket slowing to make a soft landing on Mars.
Step-by-step explanation:
In the first motion diagram, the constant speed is indicated by a horizontal line on the position-time graph. For a dust particle settling to the floor, once it reaches a constant speed, there is no further acceleration, resulting in a straight line on the graph. This corresponds to the first diagram, where the particle maintains a consistent position over time.
The second diagram, portraying uniform acceleration, is characteristic of an object in free fall, such as a ball dropped from the roof of a building. As the object accelerates uniformly due to gravity, the position-time graph displays a curved line. The slope of this curve increases over time, signifying acceleration. The second motion diagram likely represents this scenario.
The third motion diagram, showing decreasing acceleration, aligns with the behavior of a descending rocket making a soft landing on Mars. As the rocket descends, it decelerates to achieve a gentle landing. This deceleration is represented by a decreasing slope on the position-time graph. The third diagram, with its diminishing slope, is indicative of this slowing descent, characteristic of a rocket making a controlled landing on Mars.