Units and Measurements

These flashcards cover the key concepts, definitions, and important terms related to units and measurements in physical science.

Physical Quantity

Any property of a material or system that can be measured and expressed numerically along with a unit.

Numerical Value

Indicates the magnitude of the physical quantity.

Unit

Specifies the measurement standard used to quantify a physical quantity.

Fundamental Units

Standard units used to measure fundamental physical quantities such as length, mass, and time.

Derived Units

Units used to measure derived physical quantities obtained by combining two or more fundamental quantities.

SI System

International System of Units, which includes seven base units for measuring fundamental quantities.

Supplementary Quantities

Quantities essential for specific measurements that are not categorized as fundamental or derived.

Absolute Error

The magnitude of the difference between the measured value and the actual value.

Relative Error

The absolute error expressed as a fraction of the actual value.

Dimensionless Quantities

Physical quantities that have no dimensions; their dimensional formula is [M⁰ L⁰ T⁰].

Significant Figures

Digits in a number that carry meaning contributing to its measurement accuracy.

Least Count

The smallest measurement that an instrument can provide with accuracy.

Error Propagation Rule for Addition

For Z = A + B, the absolute error in Z is ΔZ = ΔA + ΔB.

Error Propagation Rule for Multiplication

For Z = A × B, the relative error in Z is the sum of the relative errors in A and B.

Dimensional Consistency

An equation is dimensionally correct only if the dimensions of each term on both sides are the same.

Pa

SI Unit of Pressure, Pascal, also known as Newton per square meter.

kg/m³

SI Unit of Density, kilograms per cubic meter.