SI Prefixes and their Values

Physical Quantities and Units

• A physical quantity consists of a numerical magnitude and a unit.
• Example: 4.5 m, where 4.5 is the numerical value and m is the unit.

SI Units and Prefixes

• The System International of Units (SI) is a system of measurement that has been agreed internationally.
• Base quantities and their units:
  • Mass: kg
  • Length: m
  • Time: s
  • Current: A
  • Temperature: K
  • Amount of substance: mol
• Prefixes and their values:
  • pico: 10^-12
  • nano: 10^-9
  • micro: 10^-6
  • milli: 10^-3
  • centi: 10^-2
  • deci: 10^-1
  • kilo: 10^3
  • mega: 10^6
  • giga: 10^9
  • tera: 10^12

Unit Conversion

• Unit conversion is often necessary in physics experiments.
• A simple method for unit conversion involves multiplying a series of factors to cancel out unwanted units.
• Example: converting 0.800 g/cm^3 to kg/m^3 using the conversions 1 kg = 1000 g and 100 cm = 1 m.

Volume Measurements

• Units for volumes include mm^3, cm^3, m^3, and km^3.
• For liquids, volume is measured in milliliters (ml) or liters (l), where 1 liter = 1000 ml = 1000 cm^3.

Measuring Apparatus

• Measuring cylinder:
  • Available in various sizes (50 ml, 100 ml, 250 ml, 500 ml, and 1000 ml).
  • Can be made from plastic and glass.
  • Accuracy: 0.5 cm^3 (depending on the smallest division).
• Burette:
  • A long, narrow cylinder with a tap at the bottom.
  • Allows liquid to flow out in drops through a jet.
  • Accuracy: 0.05 cm^3 (half the smallest division).