Understanding Measurement & Precision - ACT Science

5 kilograms. Divide grams by 1000 to get kg.

150 minutes. $2.5 \times 60 = 150$ minutes.

2 grams. Multiply kg by 1000 to get grams.

$5.6 \times 10^{-4}$. Move decimal 4 places right for negative exponent.

$\text{Volume} = \text{length} \times \text{width} \times \text{height}$. Multiply three dimensions for rectangular volume.

Meter (m). Base unit for distance measurement in SI.

Second (s). Base unit for time duration in SI.

Kelvin (K). Absolute temperature scale starting at absolute zero.

Ampere (A). Base unit for electrical flow rate.

Mole (mol). Base unit for counting particles or molecules.

$K = °C + 273.15$. Add 273.15 to convert from Celsius to absolute temperature.

$°C = (°F - 32) \times \frac{5}{9}$. Subtract 32, then multiply by $\frac{5}{9}$ to convert.

0.00457. Round the fourth digit up since the fifth is 6.

1. Count non-zero digits and zeros between them.

123.5. Round the fifth digit down since the sixth is 5.

Closeness of a measurement to the true value. Accuracy measures how close to the true value.

Repeatability or consistency of measurements. Precision measures how consistent repeated measurements are.

Systematic error. Consistent bias affects all measurements the same way.

Random error. Unpredictable variations cause random measurement differences.

Kilogram (kg). Base unit for mass in the metric system.

1.5 L. Divide by 1000 to convert milliliters to liters.

$\text{Percent Error} = \frac{\text{|Experimental - True|}}{\text{True}} \times 100$. Formula compares experimental result to true value.

1.52%. $\frac{|100.0-98.5|}{98.5} \times 100 = 1.52%$

1000 mm. Standard metric conversion: 1 m = 1000 mm.

1. Move decimal 3 places right for positive exponent.

0.00256. More decimal places means higher precision.

100 cm. Standard metric conversion: 1 m = 100 cm.

2.5 cm. Divide by 10 to convert millimeters to centimeters.

10.0 cm. 10.0 cm is exactly the true value.