Scientific Inquiry and Process Skills in Physics
Domain 1: Scientific Inquiry and Process Skills in Physics
This domain tests how physics knowledge is built and checked: experimental design, measurement, uncertainty, data display, and evidence-based conclusions. Expect items on variables, significant figures, unit analysis, graphs, and error.
Core rules
- An experiment identifies an independent variable (changed), a dependent variable (measured), and controlled variables held constant.
- Accuracy is closeness to the accepted value; precision is repeatability. Random error scatters repeated readings; systematic error shifts all readings the same way, such as an uncalibrated meter.
- Report to the least precise measurement and apply significant-figure rules separately for multiplication/division and addition/subtraction.
- Convert units by dimensional analysis so unwanted units cancel. Check that both sides of an equation have the same dimensions.
- Linearize data before interpreting slope: for y = mx + b, slope carries units of y/x. On a position–time graph, slope is velocity; area under a velocity–time graph is displacement.
- Percent error = |measured − accepted| / accepted × 100%. For repeated timing, divide total time by the number of cycles before computing the period.
Worked example
A student times 20 swings of a pendulum with a stopwatch reading to 0.1 s. The total is 32.4 s, so the period is 32.4/20 = 1.62 s. If reaction time makes the total uncertain by ±0.2 s, the period uncertainty is 0.2/20 = ±0.01 s, giving 1.62 ± 0.01 s. Timing many cycles reduces the per-cycle uncertainty; it does not remove a systematic stopwatch offset.
Traps that cost marks
- Adding raw uncertainties without considering whether they are independent.
- Treating a zero intercept as automatic; a nonzero intercept can reveal a systematic offset.
- Mixing precision and accuracy in conclusions.
- Forgetting that slope units come from the axes, not from the formula alone.