Thermal Contact
is when two substances can affect each other's temperature.
Thermal Equilibrium
is when two substances in thermal contact no longer transfer heat.
Thermal Expansion
takes place when a substance expands in volume as it gains heat. Thermal contraction also exists when heat is lost from a substance.
Conduction
is when heat flows through a heated solid.
Convection
is when heated particles transfer heat to another substance, such as cooking something in boiling water.
Radiation
is when heat is transferred through electromagnetic waves, such as from the sun.
Insulation
is when a low-conducting material is used to prevent heat transfer.
thermodynamic process
What a system undergoes a when there is some sort of energetic change within the system, generally associated with changes in pressure, volume, internal energy (i.e. temperature), or any sort of heat transfer.
heat capacity of a substance
indicates the ease with which a substance heats up. A good thermal conductor would have a low heat capacity, indicating that a small amount of energy causes a large temperature change.
A good thermal insulator
would have a large heat capacity, indicating that much energy transfer is needed for a temperature change.
The First Law of
Thermodynamics:
The change in the energy of a system is the amount of energy added to the system minus the energy spent doing work.
Heat transfer
is a process by which internal energy from one substance transfers to another substance.
Effects of Heat Transfer:
The basic effect of heat transfer is that the particles of one substance collide with the particles of another substance. The more energetic substance will typically lose internal energy (i.e. "cool down") while the less energetic substance will gain inte
A change in temperature
is associated with changes in the average kinetic energy of the particles within the object.
A change in state
is associated with changes in the internal potential energy possessed by the object.
The specific heat capacity
refers to the amount of heat required to cause a unit of mass (say a gram or a kilogram) to change its temperature by 1�C
A calorimeter
is a device used to measure the quantity of heat transferred to or from an object
Phase changes
are due to potential energy changes.
latent heat
the energy absorbed or released during a change in state
internal energy
the sum of the kinetic and potential energies of all particles in the system
joule
SI unit of energy
calorimeter
an instrument used to measure changes in thermal energy
Temperature
A measure of the average energy of motion of the particles of a substance.
kelvin
A unit of absolute temperature and symbolized as K. Formerly known as degree Kelvin.
celsius
A temperature scale in which water freezes at 0 degrees and boils at 100 degrees.
farenheit
A temperature scale in which water freezes at 32 degrees and boils at 212 degrees
heat
Energy that is transformed as a consequence of temperature differences
phase change
A transition of matter from one state to another
what is the relationship between temperature and internal energy?
temperature increases as the internal energy increases
what must be true of two objects if the objects are in a state of thermal equilibrium?
their temperatures are the same
A glass of tea has an initial temperature of 8 degrees C. In which situation will the rate of energy transfer be greater, when the airs temperature is 25 degrees C or 35 degrees C?
When the air temperature is 35 degrees C...
How much energy is transferred between a piece of toast and an oven when both are at the same temperature of 55 degrees C?
None; there is thermal equilibrium between the toast and the oven...the are both at 55 degrees C.
A floor covered with tile feels very cold to your bare feet, but a floor covered with carpet at the same room temperature feels warm to your feet. Why?
Tile is a better conductor of thermal energy therefore the energy transfer happens faster between your feet and the tile.
inernal energy
energies associated with atomic motion
translational energy
The energy of a particle moving in space. It is defined in s of a particle's mass, m, and velocity, v, as (1/2)mv2.
rotational energy
A form of kinetic energy which occurs when objects spin
vibrational energy
A form of Kinetic Energy which causes all the molecules of an object or any kind to vibrate.
example of translational energy
airplane in flight, carbon dioxide molecule in linear motion
example of rotational energy
spinning top
example of vibrational energy
plucked guitar string
celsius-fahrenheit temperature conversion
Tf=9/5 Tc + 32.0
celsius temperature conversion to fahrenheit formula
To convert to Celsius take Temperature Fahrenheit minus 32 degrees and divide by 1.8.
celsius to kelvin
K=C+273