Scientific Method, Measurement and Data flashcards

Independent (manipulated): the factor the experimenter deliberately changes, usually on the x-axis. Dependent (responding): the outcome measured, usually on the y-axis.

A control group gets no treatment and serves as the baseline (plants given plain water). Controlled variables are factors held the same for all groups (soil, light, pot size).

A hypothesis is a proposed, testable explanation of why something happens. A prediction is the specific result expected if the hypothesis is right, often written as if-then.

$\rho =\frac{m}{V}$, where $\rho$ is density, m is mass (g) and V is volume (${\text{cm}}^3$ or mL). Example: 54 g in 20 ${\text{cm}}^3$ gives 2.7 g/${\text{cm}}^3$. Water is about 1 g/mL; denser objects sink.

Accuracy: how close a measurement is to the true value. Precision: how close repeated measurements are to each other. A scale reading 105 g three times for a 100 g mass is precise but not accurate.

Systematic error shifts every reading the same way (a scale always 5 g high); fix it by recalibrating, not averaging. Random error scatters readings both ways; repeat and average to reduce it.

$\text{percent change}=\frac{\text{new}-\text{original}}{\text{original}}\times 100$. 50 to 40 is a 20% decrease; 40 to 50 is a 25% increase. The original value is the reference.

Square or cube the conversion factor too. Since 1 m = 100 cm, 1 ${\text{m}}^2$ = 10,000 ${\text{cm}}^2$ and 1 ${\text{m}}^3$ = 1,000,000 ${\text{cm}}^3$, not 100.