Scientific Inquiry
What Scientific Inquiry tests
Scientific Inquiry tests experimental design, variable control, operational definitions, data representation, uncertainty, and evidence-based conclusions. The exam asks you to judge whether a conclusion follows from the described procedure, not to recall a named experiment.
Core rules
- Identify the independent variable manipulated, the dependent variable measured, and variables held constant. A valid comparison changes one factor at a time.
- An operational definition states how a quantity is measured, not just its abstract meaning.
- Accuracy is closeness to an accepted value; precision is reproducibility. Random error scatters repeated measurements; systematic error shifts them consistently.
- Graphs should use labeled axes, units, and a best-fit relationship. A linearized graph often reveals the physical constant in its slope.
- Report uncertainty consistently and avoid overstating precision. A conclusion needs sufficient sample size and a control or comparison group.
Worked example
A student measures a pendulum’s period T at several lengths L and plots T^2 versus L. The best-fit slope is 4.0 s^2/m. Find g.
For a simple pendulum, T = 2π√(L/g), so T^2 = (4π^2/g)L. The slope is 4π^2/g. Thus g = 4π^2/4.0 = 9.87 m/s^2. The linearized plot is better than a curved T versus L plot because the slope directly gives g and deviations are easier to see.
Traps
Confusing correlation with causation; calling a precise set of measurements accurate; adding percentage uncertainties for a product when they should be combined in quadrature; ignoring a systematic offset; changing two variables in one trial; treating the slope’s units as unimportant.