Cambridge IGCSE Physics: Physical Quantities, Measurements, Mass, Volume, and Density

Vocabulary flashcards based on Cambridge IGCSE Physics Chapter 1 covering physical quantities, measurement techniques, error analysis, standard form, mass, volume, density, and floating/sinking principles.

Physical Quantity

A property of an object that can be measured.

Measuring

Comparing a standard unit of measurement with the quantity to be measured and counting how many times one is contained within the other.

SI Units (Système Internationale d'Unités)

The standardized units of measurement used by scientists all over the world.

Fundamental (Base) Units

The seven standard SI units: kilogram ($\text{kg}$), metre ($\text{m}$), second ($\text{s}$), ampere ($\text{A}$), kelvin ($\text{K}$), mole ($\text{mol}$), and candela ($\text{cd}$).

True Value

The value that would be obtained in an ideal measurement.

Measurement Error

The difference between a measured value and the true value of a quantity.

Precision (of an Instrument)

The smallest measuring interval or smallest division that a measuring device can read.

Uncertainty (Absolute Error)

Given by half the difference between the maximum value and the minimum value among multiple measurements: $e_a = \frac{x_{\text{max}} - x_{\text{min}}}{2}$.

Average (Mean) Value

The value found by summing all the measurements and dividing by the total number of measurements: $\text{average} = \frac{\text{sum}}{\text{count}}$.

Trundle Wheel

A measuring instrument used to measure long lengths or distances on the ground of tens of metres.

Vernier Calipers

A measuring instrument used to measure object lengths up to around $15\,\text{cm}$.

Micrometer

A high-precision measuring instrument used to measure small objects up to around $3\,\text{cm}$ in length.

Period of Oscillation

The time taken for a pendulum bob to swing from side to side and return back to its original position (one complete oscillation).

Standard Form (Scientific Notation)

A system in which numbers are written as a number greater than or equal to 1 and less than 10 multiplied by a power of 10 ($a \times 10^n$).

Derived Physical Quantity

A physical quantity that cannot be directly measured, but is calculated using mathematical operations between fundamental or other derived quantities.

Mass

A measure of the quantity of matter in an object at rest relative to the observer, measured in kilograms ($\text{kg}$) using a digital balance.

Volume

The space occupied by an object, measured in cubic metres ($\text{m}^3$) or cubic centimetres ($\text{cm}^3$).

Meniscus

The curved upper surface of a liquid in a container, from the bottom of which volume readings must always be taken.

Displacement Method

A technique used to find the volume of an irregularly shaped solid by measuring the volume of liquid it displaces when fully submerged.

Eureka Can

A container filled with water up to its spout used to measure the volume of an irregular solid by collecting and measuring the volume of displaced water that overflows.

Density

The mass per unit volume of a substance, calculated using the equation $\rho = \frac{m}{V}$.

Upthrust

The upward force exerted by a fluid on an object placed in it, which opposes the object's weight.

Condition for Sinking

An object sinks in a fluid if its density is greater than the density of the fluid ($\rho_{\text{object}} > \rho_{\text{fluid}}$).

Condition for Floating

An object floats in a fluid if its density is less than the density of the fluid ($\rho_{\text{object}} < \rho_{\text{fluid}}$).

Significant Figures

The number of digits kept as important during the rounding of a number to reflect the precision of the measuring instrument.

Trailing Zeros

Zeros located after the last non-zero digit in a number with a decimal point, which are counted as significant figures.