19.1 Flashcards
Internal energy and temperature
when does energy transfer between two objects take place
if one objects exerts a force on the other object casting it to move ( does work on the other object)
if one object is hotter than the other object so the energy transfer of heat takes place via conduction, convection or radiation 9 energy is transferred due to the temperature difference)
explanation of why brakes heat up
the world done by the frictional force between the brake pads and the tyres heats the break pads which gain energy from the kinetic energy of the vehicle
temp increases and the internal energy of the break pad increases
what is the internal energy of an object due to its temperature called
thermal energy
what is the internal energy of an object increased because of
energy transfer by heating the object
work done on the object
what does it mean if the internal energy of an object stays constant
no energy is transferred by heating and no work is done
energy transferred by heating and work done balance each other out
the first law of thermodynamics
the change of internal energy of an object =
the total energy transfer due to work done and heating
why are the atoms in a solid held together
due to the forces of attraction between the electrical chases of protons and electrons
what are the molecules in a solid like
vibrate in a fixed position in a neat arrangement
what happens when particles gain in a solid heat up
they gain more kinetic energy and begin to vibrate
eventually the solid will melt when the bonds break between the molecules and they begin to move freely over each other
what does the energy supplied to melt a solid do to the potential energy of the molecules
raises them because they break free from each other
what are molecules like in a liquid
move about at random in contact with eachother
can move over each other
the forces between the molecules are not strong enough to hold them in fixed positions
when the temperature of a liquid is raised the kinetic energy of the liquid increases and the particles have sufficient energy to break away from each other and vaporise the liquid
molecules in a gas
move in random speeds in random directions further apart than in a liquid
heating a gas causes the particles to gain kinetic energy and speed up
what is the internal energy of an object
the sum of the random distribution of the kinetic and potential energies of molecules
hotter object =
more internal energy
what is thermal equilibrium
when no overall heat transfer occurs because the objects are at the same temperature
0 degrees celcius =
the temperature at which pure ice melts
100 degrees c =
the temperature of steam at standard atmospheric pressure
what is the absolute scale measured in
Kelvins
what is 0 K
absolute 0 with is the lowest posible temperature
what is the triple point of water
273.16 which is the point where ice, water and water vapour coexist in thermodynamic equilibrium
when 0k what is it in degrees
-273.15
when 373K what is it in degrees
100
what does the absolute 0 temp mean
no object can have a temp below thus. the object has minimum internal energy
how was the value -273 found
if a gas is placed in a sealed container and the pressure is measured of it at ice point and steam point is measured they will always cut the temp axis at this point despite which gas is used
