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Experimental Design and Scientific Method

201 soru

Tüm türler201Çoktan seçmeli119Doğru / Yanlış4Eşleştirme64Sıralama14
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A researcher is reviewing several experimental setups to ensure that all potential confounding variables are properly controlled. Match each experimental procedure to the specific uncontrolled variable or source of error that threatens the validity of its findings.

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Öğeler

Measuring how the length of a pendulum string affects its period of oscillation, while releasing the pendulum bob from a different starting angle for each length tested.
Comparing how quickly different solutes dissolve in water, while stirring the mixture rapidly for some solutes and leaving others completely still.
Measuring the rate of water drainage through different soil types, while packing the soil samples to different densities in their columns.
Investigating osmosis by placing potato cylinders in sucrose solutions of different concentrations, while using potato cylinders cut to different surface-area-to-volume ratios.

Eşleşmeler

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Cevap

The pendulum length experiment matches the starting angle confound; the solute dissolution experiment matches the stirring rate confound; the soil permeability experiment matches the compaction density confound; and the potato osmosis experiment matches the surface-area-to-volume ratio confound.
Each experimental setup introduces a specific uncontrolled variable that interferes with the relationship between the independent and dependent variables. By matching the physical properties of the error to the specific experimental system, we identify how each confounding factor compromises the results.

Adım Adım Çözüm

1
Analyze each experimental procedure to identify the independent variable and the intended dependent variable.
For each setup, the independent variable (pendulum length, solute type, soil type, sucrose concentration) is varied to measure a dependent variable (period, dissolution speed, drainage rate, osmosis rate).
Understanding the intended relationship helps pinpoint variables that should be controlled but are instead being varied.
2
Identify the uncontrolled variable in each procedure that varies alongside the independent variable.
The uncontrolled variables are: starting angle (pendulum), stirring rate (dissolution), packing density (soil drainage), and cylinder dimensions/surface-area-to-volume ratio (osmosis).
An uncontrolled variable that changes systematically with the independent variable is a confounding variable.
3
Match each uncontrolled variable to its physical consequence on the experimental measurement.
Starting angle affects potential energy/amplitude; stirring affects convective transport/dissolution rate; packing density affects pore space/flow resistance; surface-area-to-volume ratio affects diffusion rate per unit volume.
This establishes the physical mechanism by which the confounding variable compromises the validity of the results.

Anahtar Kavram

Identifying Sources of Error and Confounding Variables
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Experimental Design and Scientific Method Alıştırma Soruları — ACT — Sayfa 11 | Examkin