Chapter 2: Units and Measurement
Fundamental Units
- Mass - Kilogram
- Length - Meter
- Time - Second
- Temperature - Kelvin
- Electric Current - Ampere
- Luminous Intensity - Candela
- Amount of Substance - Mole
Derived Units
- Speed
- Velocity
- Acceleration
- Force
Supplementary Units
- Plane Angle - Radian
- Solid Angle - Steradian
Properties of Units
- Well Defined
- Not Change with Time
- Not Perishable
- Universally Acceptable
System of Units
Complete set of fundamental and derived units
- SI System
- MKS System
- CGS System
- FPS System
Significant Figures
- All non-zero digits
- All zeros between non-zero digits
- Trailing zeros in a decimal number
Dimensions
Powers to which fundamental quantities are raised to represent a physical quantity
- Example: Force [MLT^-2]
- Work Done [ML^2T^-2]
Applications
- To convert physical quantity
- To check correctness of equations
- To derive relations between physical quantities
Important Formulas
- Density = Mass/Volume
- Speed = Distance/Time
- Acceleration = Change in Velocity/Time
- Force = Mass x Acceleration
Important Questions
- What are the fundamental units of measurement?
- Explain the difference between fundamental and derived units.
- How are significant figures determined?
- What is the importance of dimensions in physics?
Key Points
- Fundamental units are the basic units of measurement.
- Derived units are combinations of fundamental units.
- Significant figures are important for precision in measurements.
- Dimensions help in deriving and checking equations.