QCAA Physics - Unit 1 Topic 1 - Thermal Physics

Kinetic Particle Model of Matter

a model in which matter is made up of particles that are constantly moving (Tipler & Mosca 2003, Giancoli 2008)

Thermal energy

the internal energy present in a system due to its temperature (symbol, 𝑈; SI unit, J); transfer of thermal energy when heating or cooling a substance has the symbol Q in the equation 𝑄=𝑚c∆𝑇 (Tipler & Mosca 2003, Giancoli 2008)

Temperature

the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale, e.g. the Celsius temperature scale (Tipler & Mosca 2003, Giancoli 2008). SI units is kelvins, K. Equation to convert between Kelvins and Celcius 𝑇_𝐾=𝑇_𝐶+273

Kinetic Energy

the energy resulting from the movement of an object. When associated with temperature, kinetic energy is associated with the motion of particles in a substance (symbol, 𝐸_𝑘; SI unit, J) (Tipler & Mosca 2003, Giancoli 2008)

Heat

the energy transferred from one system to another because of a difference in temperature (Tipler & Mosca 2003)

Internal Energy

the total potential energy and kinetic energy of the particles in a system (Tipler & Mosca 2003, Giancoli 2008). Internal Energy = ∆𝑈+𝐸_𝑘

Conduction (Heat)

the process by which heat is directly transferred or transmitted through the material of a substance when there is a difference of temperature between adjoining regions, without movement of the material (Tipler & Mosca 2003, Giancoli 2008)

Convection

the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat (Tipler & Mosca 2003, Giancoli 2008)

Radiation

the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles, which cause ionisation (Tipler & Mosca 2003, Giancoli 2008)

Specific Heat Capacity

the amount of thermal energy transfer necessary to raise the temperature of one kilogram of a substance by one degree (symbol, c; SI unit, J kg^-1 K^-1) (Tipler & Mosca 2003, Giancoli 2008). It is the "c" in 𝑄=𝑚c∆𝑇

Specific Latent Heat

the amount of energy transfer necessary to change the state of one kilogram of a substance with no change in its temperature (Tipler & Mosca 2003, Giancoli 2008). It is the "L" in 𝑄=𝑚𝐿

Thermal Equilibrium

the condition of a system in which there is no net exchange of thermal energy between any of its components, i.e. the components have the same temperature and the average kinetic energy of their particles is equal; this relates to the zeroth law of thermodynamics (Tipler & Mosca 2003, Giancoli 2008)

Zeroth Law of Thermodynamics

the transfer of energy from a system with higher temperature to a system with lower temperature until thermal equilibrium is reached (Tipler & Mosca 2003, Giancoli 2008)

System

a group of interacting objects, materials or processes that form an integrated whole; systems can be open or closed (ACARA 2015c)

First Law of Thermodynamics

when energy passes, as work, 𝑊, or heat, 𝑄, into or out of a system, the system's internal energy changes, ∆𝑈, in accordance with the law of conservation of energy (Tipler & Mosca 2003, Giancoli 2008) ∆𝑈=𝑄+𝑊

Law of conservation of energy

the total energy of a system remains constant; energy can neither be created nor destroyed, rather, it transforms from one form to another (Tipler & Mosca 2003, Giancoli 2008)

Efficiency

the ratio of useful work performed by a machine or in a process, to total energy expended or heat taken in (Tipler & Mosca 2003, Giancoli 2008). 𝜂 = (energy output)/ (energy input) × 100%

Latent heat of fusion

refers to the amount of energy transfer necessary to change one kilogram of a substance from solid to liquid (symbol, 𝐿_𝑓; SI unit, J kg^-1) (Tipler & Mosca 2003, Giancoli 2008)

Latent heat of vaporisation

refers to the amount of energy transfer necessary to change one kilogram of a substance from liquid to gas (symbol, 𝐿_𝑣; SI unit, J kg^-1) (Tipler & Mosca 2003, Giancoli 2008)