International System of Units (SI) Fundamentals

Fundamental Units

• There are seven fundamental units in the International System of Units (SI):
  1. Meter (m) - length
  2. Kilogram (kg) - mass
  3. Second (s) - time
  4. Kelvin (K) - thermodynamic temperature
  5. Ampere (A) - electric current
  6. Mole (mol) - amount of substance
  7. Candela (cd) - luminous intensity

Derived Units

• Derived units are formed by combining fundamental units:
  • Velocity: meter per second (m/s)
  • Acceleration: meter per second squared (m/s²)
  • Force: newton (N) = kilogram meter per second squared (kg·m/s²)
  • Energy: joule (J) = newton meter (N·m) or kilogram meter squared per second squared (kg·m²/s²)

Prefixes

• Prefixes are used to denote multiples and fractions of units:
  • SI prefixes:
    • Kilo- (k): 10³
    • Centi- (c): 10⁻²
    • Milli- (m): 10⁻³
    • Micro- (μ): 10⁻⁶
    • Nano- (n): 10⁻⁹
  • Other prefixes:
    • Deci- (d): 10⁻¹
    • Hecto- (h): 10²

Conversion between Units

• Conversion between units involves multiplying or dividing by a conversion factor:
  • Example: 1 meter = 100 centimeters (cm)
  • Conversion factor: 1 m = 100 cm/m
  • To convert 5 m to cm: 5 m × (100 cm/m) = 500 cm

Fundamental Units

• There are 7 fundamental units in the International System of Units (SI)
• Meter (m) is the unit of length
• Kilogram (kg) is the unit of mass
• Second (s) is the unit of time
• Kelvin (K) is the unit of thermodynamic temperature
• Ampere (A) is the unit of electric current
• Mole (mol) is the unit of amount of substance
• Candela (cd) is the unit of luminous intensity

Derived Units

• Derived units are formed by combining fundamental units
• Velocity is measured in meter per second (m/s)
• Acceleration is measured in meter per second squared (m/s²)
• Force is measured in newton (N) or kilogram meter per second squared (kg·m/s²)
• Energy is measured in joule (J) or kilogram meter squared per second squared (kg·m²/s²)

Prefixes

• Prefixes are used to denote multiples and fractions of units
• Kilo- (k) denotes 10³
• Centi- (c) denotes 10⁻²
• Milli- (m) denotes 10⁻³
• Micro- (μ) denotes 10⁻⁶
• Nano- (n) denotes 10⁻⁹
• Deci- (d) denotes 10⁻¹
• Hecto- (h) denotes 10²

Conversion between Units

• Conversion between units involves multiplying or dividing by a conversion factor
• 1 meter is equal to 100 centimeters (cm)
• Conversion factor: 1 m = 100 cm/m
• To convert 5 m to cm: 5 m × (100 cm/m) = 500 cm

Test your knowledge of the seven fundamental units in the International System of Units (SI) and their derived units. Learn to distinguish between meters, kilograms, seconds, and more!