A physical quantity is a property of a material or system that can be quantified by measurement. To measure any quantity, we need a standard reference called a Unit.
Fundamental Quantities: Quantities that are independent of other quantities (e.g., Mass, Length, Time).
Derived Quantities: Quantities that are derived from fundamental quantities (e.g., Velocity = Length/Time, Force = Mass × Acceleration).
The internationally accepted system of units. It has 7 base units:
No measurement is perfectly accurate. The difference between the true value and the measured value is called an error.
1. Systematic Errors: Errors that tend to be in one direction (either positive or negative). E.g., zero error in an instrument.
2. Random Errors: Errors occurring irregularly due to random and unpredictable fluctuations.
Dimensions represent the nature of a physical quantity. We use square brackets [ ] to denote dimensions.
Velocity: [M⁰ L¹ T⁻¹]
Acceleration: [M⁰ L¹ T⁻²]
Force: [M¹ L¹ T⁻²]
Work/Energy: [M¹ L² T⁻²]