### HELP: Science Measurement Review & Additional Resources

#### Summary

• Measurements (quantitative observations) are more useful than qualitative observations.
• You should make measurements, even estimated ones, whenever possible.
• The system of units for measurements in physics is the SI system.
• At this time, the fundamental quantities are length, mass, and time.
• The SI unit for length is the meter and the standard meter is the distance light travels in $\frac{1}{299792458}$ second in a vacuum.
• The SI unit for time is the second and the standard second is based on of the frequency of one type of radiation emitted by a cesium-133 atom.
• The SI unit for mass is the kilogram and is based on a mass stored in France.
• Prefixes are used to change SI units by powers of ten.