A unit is a basic, internationally accepted standard for measuring a physical quantity.

Fundamental units are the basic units for measuring fundamental physical quantities such as length, mass, and time.

The SI system (Système Internationale d’Unites) is the internationally accepted system for measurement, established for consistency.

Length (metre), Mass (kilogram), Time (second), Electric Current (ampere), Temperature (kelvin), Amount of substance (mole), and Luminous Intensity (candela).

1 metre is defined based on the speed of light, fixed at 299792458 m/s.

Significant figures indicate the precision of a measurement, including all reliable digits and the first uncertain digit.

Scientific notation expresses numbers as a product of a coefficient and a power of ten, simplifying their representation.

Consider all non-zero digits, zeros between non-zero digits, and trailing zeros in a decimal; leading zeros are not significant.

Dimensional analysis involves checking the dimensions of physical quantities to ensure equations are dimensionally consistent.

Mass is the amount of matter in an object (measured in kg), while weight is the force acting on that mass due to gravity (measured in newtons).

A common mistake is reporting results with more significant figures than the least precise measurement.

A dimensional formula expresses a physical quantity in terms of its base units, e.g., velocity = [L T^-1].

Order of magnitude is a way of comparing sizes of quantities, often expressed as a power of ten.

Only quantities with the same dimensions can be added or subtracted in equations.

Results from calculations should not exceed the significant figures of the least precise measurement used in the calculation.

A dimensionless quantity has no units, often expressed as a ratio of similar physical quantities like refractive index.

Mismanagement of units can lead to incorrect results, stressing the importance of consistent unit usage.

Rounding off must preserve significant figures to ensure correct representation of measurement precision.

Changing units does not affect the number of significant figures in a measurement; only the unit representation changes.