Thermal Energy, Heat and Temperature

Vocabulary flashcards covering key terms related to thermal energy, heat transfer, temperature measurement, and related phenomena from the Grade 10 Science lecture.

Thermal Energy

The total kinetic energy of all molecules in a substance; depends on both mass and average molecular speed.

Temperature

An index of the average kinetic energy of the molecules of a substance; measured in °C or Kelvin (K).

Absolute Zero

The theoretical temperature (0 K or –273.15 °C) at which a substance would have zero thermal energy and molecular motion would cease.

Heat

The amount of thermal energy transferred from one place or object to another because of a temperature difference; measured in joules (J).

Conduction

Method of heat transfer through direct contact, where energy moves from hotter to colder regions within a solid.

Convection

Heat transfer through the bulk movement of fluids (liquids or gases) caused by density differences.

Radiation (Heat)

Transfer of heat via electromagnetic waves, requiring no medium; e.g., heat felt from the Sun.

Thermal Equilibrium

State reached when two bodies in contact attain the same temperature and no net heat flows between them.

Thermal Expansion

Increase in the volume of most substances when heated because molecules move farther apart.

Anomalous Expansion of Water

Unique property where water contracts from 0 °C to 4 °C (becoming densest at 4 °C) and expands both above and below that range.

Specific Heat Capacity

Amount of heat required to raise the temperature of 1 kg of a substance by 1 °C; unit J kg⁻¹ °C⁻¹.

Heat Equation

Q = m s (ΔT), relating heat (Q) absorbed or released to mass (m), specific heat capacity (s) and temperature change (ΔT).

Kelvin (K)

The SI unit of temperature; 0 K equals –273.15 °C.

Joule (J)

The SI unit of energy, including heat.

Sea Breeze

Daytime wind that blows from the sea toward land because land heats up faster than water due to lower specific heat capacity.

Land Breeze

Nighttime wind that blows from land to sea because land cools faster than water.

Liquid-in-Glass Thermometer

Thermometer that uses expansion of a liquid (usually mercury) in a bulb and capillary tube to indicate temperature.

Digital Thermometer

Electronic thermometer using a thermistor; temperature is displayed numerically based on changes in electrical resistance.

Radiation Thermometer

Non-contact thermometer that measures temperature from intensity of infrared radiation emitted by an object.

Calibration (of Thermometer)

Process of fixing the thermometer scale by marking lower and upper fixed points (0 °C ice point and 100 °C steam point) and dividing the interval evenly.

Direction of Heat Flow

Heat always flows spontaneously from a body at higher temperature to one at lower temperature until equilibrium is reached.