Temperature: the average kinetic energy of the particles of a substance ($J$)
temperature of object depends on average of particles but not on their potential energies
two objects are in thermal equilibrium when their temperatures are equal, and heat transfer between the objects reaches equivalent rates between the two objects
Internal Energy: the sum of the potential and kinetic energies of the particles
Heat: Thermal energy which is transferred from a hotter object to a cooler one.
consider probability; it is more likely for hot to cold than cold to hot
Kinetic theory of matter
Basic assumptions
All matter consists of tiny particles, such as atoms, molecules and ions
Electrical forces, both attractive and repulsive, exist between the particles
All particles move (for our intents and purposes) randomly and hence all possess kinetic energy (unless they are at absolute zero)
Collisions between particles involve no loss of kinetic energy, except where they lead to chemical reactions: particle collisions are said to be perfectly elastic
Liquid: particles are attracted to each other but are able to move past each other i.e. there is a continual breaking and making of bonds
Gas: particles are not attracted to each other, there is no fixed volume/shape,
Problem Set
10.1
a) thermal energy is produced by solar radiation
b) electrical energy
c) friction produced by kinetic energy of the vehicle
10.2
21.8%
10.3
The environment is warmer, that is, the gases in the atmosphere have a higher temperature. Due to this, it's heat is higher and so the engines of the cars that are running increase in temperature
10.4
a) 60%
b) An experiment could measure the motion of the ball over a certain period of time, and use the SUVAT equations
c) It is converted into kinetic energy; both within the ball (internal energy increasing its temperature and heat) and sound in the form of mechanical waves.
10.5
a) thermal energy
b) it increases the internal energy and thus temperature of the brake discs, increasing its heat, which leads to energy being dissipated into the surrounding environment
10.6
Since the freezer has low internal energy, it's temperature is low, and thus heat will transfer from the surroundings into the freezer, leading to the room becoming cooler.
10.7
A heat 'pump' does exactly that - instead of turning some form of energy into internal energy in the gases of the room, it simply uses energy to transfer internal energy from some place into the room, thus making it appear as if more energy is produced than put in
10.8
a) The existence of heat leads to a higher entropy in a system. Thus, thermal energy is a type of low grade energy
b) It has a higher entropy, a higher level of disorder, randomness and a lower level of control
c) A uranium pellet, which has not been doped.
10.9
Thermal Conductivity & Expansion
Poor electrical conductors tend to be poor thermal conductors
they use mobile particles as a mechanism to transfer energy, such as electrons
Thermal expansion refers to particles in a substance gaining thermal energy, leading to particles vibrating more (as per the kinetic theory of matter), thus expanding more in every dimension
can cause problems - e.g. railroad tracks
Thermal Equilibrium
Two substances in contact (easy to picture solids, but can be any state) which are of different temperatures will continuously transfer heat from hotter to colder substances (most likely - it can happen the other way in the zany zone) until they reach thermal equilibrium i.e. the same temperature
Specific Heat Capacity
The amount of energy required to raise the temperature of 1kg of a substance by 1KF
The practical
$3.2$ in STAWA
go to room AU23
wherever they mention nickel, ignore it
we're using stainless steel; it has corrosion so the specific heat capacity will be different to normal stainless steel
even if the numbers are way off, do it anyway
also stawa sets it up on a weird angle.
instead we have the gauze, bunsen, tripod. however we want a clap holding the test tube and stuff
nestle the thermometer as deep as possible amongst the metal beads within the test tube