Unit 1 – Physical Quantities and Measurement (Vocabulary Review)

These vocabulary flashcards cover the fundamental terms and instruments introduced in Unit 1: Physical Quantities and Measurement, including SI units, measurement tools, error types, and rules for scientific notation and significant figures.

Physics

The fundamental natural science that studies matter, energy, and their interactions.

Physical Quantity

A property of matter or energy that can be measured and expressed with a number and a unit (e.g., length, mass).

Non-Physical Quantity

A property that cannot be measured with instruments (e.g., taste, feeling).

Measurement

The comparison of an unknown physical quantity with a standard unit to determine its magnitude.

Unit

An agreed-upon standard used to express a physical quantity (e.g., metre, second).

Base Physical Quantity

One of the seven fundamental quantities chosen in SI from which all others are derived (length, mass, time, etc.).

Derived Physical Quantity

A quantity obtained by multiplying or dividing base quantities (e.g., velocity, force).

System International (SI)

The internationally accepted system of units based on seven base units and their multiples.

SI Base Unit

A standard unit assigned to each base quantity in SI (metre, kilogram, second, ampere, kelvin, mole, candela).

SI Derived Unit

A unit formed from base units by multiplication or division (e.g., newton = kg·m·s⁻²).

Scientific Notation (Standard Form)

A method of writing very large or small numbers as M × 10ⁿ, where 1 ≤ M < 10.

Mantissa

The decimal number (1 to <10) in scientific notation (e.g., 8.8 in 8.8 × 10²⁶).

Exponent

The power of ten that shows how many places the decimal is moved in scientific notation.

Prefix (SI Prefix)

A word or symbol added to a unit to represent a specific power of ten (e.g., kilo-, micro-).

Scalar Quantity

A physical quantity fully described by magnitude and unit only, with no direction (e.g., speed, time).

Vector Quantity

A physical quantity described by magnitude, unit, and direction (e.g., velocity, force).

Resultant Vector

The single vector that has the same effect as two or more vectors added together.

Coordinate System

A pair of perpendicular axes (x, y) used as a reference frame to specify positions and directions.

Least Count

The smallest value that can be measured directly on the scale of an instrument.

Metre Rule

A rigid one-metre scale, typically graduated in millimetres; least count = 1 mm.

Measuring Tape

A flexible ruler marked in linear units for measuring larger or curved lengths.

Vernier Caliper

An instrument with a main scale and a sliding vernier scale for measuring lengths to fractions of a millimetre.

Vernier Constant (Least Count of Vernier)

The smallest measurement a vernier caliper can read, equal to one main-scale division divided by the number of vernier divisions.

Zero Error (Vernier/Screw Gauge)

The error present when the zero of the sliding scale does not coincide with the zero of the main scale when jaws are closed.

Screw Gauge (Micrometer)

A precision instrument that measures very small lengths using a calibrated screw mechanism.

Pitch (Screw Gauge)

The distance the spindle moves forward in one complete rotation of the screw.

Physical Balance

A beam balance with two pans used to determine mass by comparing with standard weights.

Measuring Cylinder

A graduated container for measuring liquid volume; typical least count = 1 cm³ (1 mL).

Stop Watch

A timing device used to measure short time intervals; may be analogue (1 s LC) or digital (0.1 s LC).

Systematic Error

A consistent, repeatable error caused by faulty instruments, procedure, or bias, affecting accuracy.

Random Error

An unpredictable variation in measurements due to uncontrollable factors, affecting precision.

Precision

The degree to which repeated measurements under unchanged conditions show the same results.

Accuracy

The closeness of a measured value to the true or accepted value.

Significant Figures

All reliably known digits in a measurement plus the first doubtful digit, indicating precision.

Rounding Off

The process of reducing the number of digits in a value while keeping it representative of its precision.