Chapter 19 - Thermal physics Flashcards
What is internal energy?
Internal energy is the sum of the randomly distributed kinetic and potential energies of the particles in a body.
How is the internal energy of a system increased?
The internal energy of a system is increased when energy is transferred to it by heating or when work is done on it.
What is thermal equilibirum?
The state in which there is no net flow of thermal energy between the object involved.
Objects in thermal equilibrium must be the same temperature.
What is heat?
Heat is defined as a spontaneous flow of energy (hot to cold) from one object to another, caused by a difference in temperature between two objects; so objects do not possess heat.
What is absolute zero?
The temperature at which the particles have zero kinetic energy (0K) and are completely stationary.
What is the specific heat capacity of a substance?
The energy required to change the temperature of unit mass of a substance by 1K without change of state.
What is the specific latent heat of a substance?
The energy required per unit mass to change its state without changing its temperature.
What is the name for the specific latent heat during a change of state from solid to liquid?
Specific latent heat of fusion
-ve for Liquid → Solid
What is the name for the specific latent heat during a change of state from liquid to gas?
Specific latent heat of vaporisation
-ve for Gas → Liquid
What causes a change of state from solid to liquid to gas?
Substances change state from solid to liquid to gas as the increasing potential energies of the particles overcome the intermolecular forces causing the substance to be at that state.
