vocab Flashcards
Newtons law of cooling
The rate of loss of heat from an object is proportional to the temperature difference between the object and its surroundings.
first law of thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed.
Carnot efficiency
Ideal maximum percentage of input energy that can be converted to work in a heat engine. Can NEVER be 100% efficient.
Heat engine
a device that converts thermal energy into mechanical energy, or work
Heat pump
a device that uses work to transfer thermal energy from a colder area to a warmer area. Examples include refrigerators and air conditioners.
entropy
A measure of disorder or randomness of a system
The second law of thermodynamics
Heat flows from warm to cold.
Work is needed to reverse this flow.
Entropy in a closed system increases over time
The third law of thermodynamics
entropy of a perfectly organized crystal at absolute zero is zero
Zeroth Law of Thermodynamics
Two objects in contact with each other, are in thermal equilibrium when they both reach the same temperature.
Specific heat capacity/specific heat
c, the quantity of heat needed to raise the temperature of 1g of the substance by 1K
delta T
change in temperature (Tf-Ti)
Heat Transfer: Convection
Heat transfer through movement of liquid or gaseous matter from a hot to a cool region
EX: warm air/water rises, cold air/water sinks
Thermal Conductivity
the rate at which a substance transfers heat
Metal is a good thermal conductor
Wood is poor thermal conductor
Specific heat
The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius
Higher specific heat
the longer it takes for a material to heat up and cool down.
Heat
The energy transferred between objects that are at different temperatures
Thermal energy
The total energy of all the particles of an object.
High specific heat capacity
A material or substance that will heat up and cool down more SLOWLY than a material with “LOW” specific heat capacity. WATER!! (in other words it takes a long time for water to heat up and a long time for water to cool down)
Heat Transfer: Conduction
-process of transferring heat/electricity through a substance
-conduction occurs when 2 solid materials of differing temperatures are placed in contact with each other & heat flows from the hotter to the colder object
Heat Transfer: Radiation
Radiation doesn’t require a medium for heat to be exchanged. Energy in the form of electromagnetic waves. It is energy which can travel at high speeds through empty space.
EX: heat from sun, seen in medicine
