25. A scientist wants to determine how the speed of flowing water affects the size of sediment particles it can carry. The scientist places a mix of sediment particles in the bottom of a trough and runs water through the trough. The scientist varies the speed of the water and measures the sizes of the particles that the water carries away. Which type of investigation is the scientist using?
Answer: A
The scientist is using a controlled experiment.
In this investigation, the scientist is manipulating the speed of the water while measuring the resultant size of sediment particles carried away. This approach characterizes a controlled experiment as it involves changing one variable (water speed) to observe its effect on another variable (sediment size).
A) Controlled experiment
This option is correct because the scientist systematically changes the speed of the flowing water to observe the impact on sediment particle size. By controlling the water speed and keeping other conditions constant, the scientist can establish a clear cause-and-effect relationship.
B) Field study
This option is incorrect because a field study typically involves observing subjects in their natural environment without manipulation of variables. In this case, the scientist is actively manipulating the speed of the water, which does not align with the concept of a field study.
C) Observational study
This option is incorrect as an observational study relies on observing and recording data without any intervention. The scientist’s method includes manipulation of water speed, indicating that this is not a passive observation, but rather an active investigation.
D) Computational model
This option is also incorrect because a computational model involves simulating a scenario through calculations or algorithms rather than conducting a physical experiment. The scientist’s approach requires physical interaction with sediment and water, thus ruling out computational modeling.
Conclusion
The controlled experiment is the definitive answer as it involves the manipulation of a variable to observe its effects, which is precisely what the scientist is doing with the water speed and sediment sizes. All other options fail to accurately describe the nature of the investigation, as they either lack experimental manipulation or involve different methodological approaches.