Energy in Thermal Physics

These flashcards cover key vocabulary and concepts in thermal physics, focusing on definitions and explanations relevant to temperature, heat transfer, and thermodynamics.

Thermal Equilibrium

When two objects are in contact long enough, they reach the same temperature.

Relaxation Time

The time required for a system to come to thermal equilibrium.

Thermometer

A device used to measure temperature, typically using thermal expansion of a substance.

Operational Definition of Temperature

Temperature is what you measure with a thermometer.

Theoretical Definition of Temperature

Temperature is the measure of the tendency of an object to spontaneously give up energy to its surroundings.

Thermal Insulation

Materials that reduce the transfer of heat between objects, preventing thermal equilibrium.

Diffusive Equilibrium

A state where substances in contact mix but do not have a tendency to move in a particular direction.

Mechanical Equilibrium

A state where large-scale motions can take place but do not occur.

Exchanged Quantity in Thermal Equilibrium

The quantity exchanged between systems in thermal equilibrium is energy.

Kelvin

The SI unit of absolute temperature; defined as degrees above absolute zero.

Celsius Scale

A temperature scale defined by the freezing and boiling points of water.

Absolute Zero

The temperature at which a system has minimum thermal energy; 0 K or -273.15 °C.

Ideal Gas Law

A law stating the relationship between pressure, volume, temperature, and amount of a gas (PV = nRT).

Mole

A unit of measure for the amount of substance; defined as Avogadro's number (6.02 x 10²³) of particles.

Avogadro's Number

The number of atoms or molecules in one mole of a substance, approximately 6.02 x 10²³.

Boltzmann's Constant

A physical constant that relates the average kinetic energy of particles in a gas with the temperature of the gas.

Thermal Expansion Coefficient

A measure of how much a material expands per degree of temperature increase.

Equipartition Theorem

A principle stating that energy is distributed equally among all degrees of freedom at thermal equilibrium.

Heat

The spontaneous transfer of energy between two objects at different temperatures.

Work in Thermodynamics

Transfer of energy into or out of a system, not caused by temperature differences.

First Law of Thermodynamics

The principle stating that energy cannot be created or destroyed, only transformed.

Heat Capacity

The amount of heat required to change the temperature of an object by one degree.

Specific Heat Capacity

The heat capacity per unit mass of a material.

Latent Heat

The heat required to change the phase of a substance without changing its temperature.

Enthalpy

The total energy of a system, equal to the internal energy plus the product of pressure and volume.

Fourier's Law of Heat Conduction

A law stating that the rate of heat transfer through a material is proportional to the temperature gradient.

Viscosity

A measure of a fluid's resistance to flow and deformation.

Fick's Law

A law describing the diffusion process, stating that the particle flux is proportional to the concentration gradient.

Mean Free Path

The average distance a molecule travels before colliding with another molecule.

Diffusion Coefficient

A constant that quantifies the rate at which particles diffuse.