[TP] thermal physics Flashcards
what is the kinetic theory of matter?
the kinetic theory of matter states that matter is made up of tiny particles that are in constant random motion
what are the characteristics of the three states of matter?
difference in shape, volume, ease of flow and compressibility
describe the characteristics of a solid
- fixed shape
- fixed volume
- do not flow
- not compressible
describe the characteristics of a liquid
- do not have fixed shape, they take the shape of their container
- have a fixed volume
- flows
- not compressible
describe the characteristics of a liquid
- do not have fixed shape (takes the shape of their container) and volume
- flows
- compressible
what is the attraction between particles in a solid?
there are strong forces of attraction between particles in a solid
what is the attraction between particles in a liquid?
the force of attraction is weaker than in gas but stronger than in gas
what is the attraction between particles in a gas?
the particles in a gas experience very weak forces of attraction
how are particles arranged in a solid?
particles in a solid are arranged in a fixed, regular pattern
how are particles arranged in a liquid?
particles are slightly further apart than in solid, closer than in gas
how are particles arranged in a gas?
particles in a gas have no fixed positions and no regular pattern
how do particles in a solid move?
particles in a solid vibrate about fixed positions
how do particles in a liquid move?
particles in a liquid slide past one another
how do particles in a gas move?
particles in a gas move freely and randomly at high speeds, occupying any available space
what happens to matter when it is heated?
it gains heat and expands
what happens to matter when it is cooled?
it loses heat and contracts
does the mass of matter change when it expands or contracts?
no - the mass remains the same
why does matter expand when heated?
heating adds thermal energy, causing particles to vibrate more and move apart
why does matter contract when cooled?
cooling removes thermal energy, causing particles to vibrate less and move closer together
what are some negative effects of thermal expansion?
some examples are road cracking on hot days and warping of materials like railway tracks
what is heat?
heat is the transfer of thermal energy from hot to cold regions
what is temperature?
temperature is the measure of hotness and coolness
what is conduction?
conduction is the transfer of thermal energy without the physical movement of the medium and is most effective in solids
what is temperature measured in?
it is measured in Kelvin(K)
what are some other units of temperature?
degree fahrenheit and degree celsius
how does temperature relate to the average speed of particles in a substance?
higher temperature =. higher average speed
lower temperature = lower average speed
does the temperature of an object depend on its size or material?
no, temperature is independent of size or material
how does the size of an object relate to the amount of thermal energy it contains?
larger objects contain more thermal energy due to their greater volume
what is conduction?
conduction is the transfer of thermal energy without the movement of the medium. it can occur in any state of matter.
why is conduction most effective in solids?
in solids, particles are closely packed, allowing for faster energy transfer through vibrations
why are air and water poor conductors of heat?
in fluids, particles are spaced further apart, resulting in slower energy transfer through collisions between the particles
explain the transfer of thermal energy through conduction
particles at the hotter end gain energy, vibrate more vigorously, and transfer kinetic energy to neighbouring particles through collisions
what are good conductors of heat, and why
materials that allow more heat transfer
this is because they possess free moving electrons that help transmit energy
what are poor conductors of heat, and why
materials that allow little heat transfer
this is because they lack free-moving electrons and hinder energy transmission
what is convection?
convection is the transfer of thermal energy by the physical movement of a medium and occur in liquids and gases.
how does convection work in a liquid/gas
the fluid at the bottom will gain heat and expand, becoming less dense and rises
the cooler denser fluid will sink, creating a convection current that transfers heat
why is the cooling unit at the top in a refrigerator?
cool air being denser sinks to cool the contents, while warmer air warmed by the contents rises and is cooled by the unit. this creates a convection current
what is radiation?
radiation is the transfer of thermal energy from a hotter body to a cooler body without a medium, and it can pass through a vacuum.
what four factors affect the rate of heat transfer by radiation?
surface colour, texture, temperature and the material’s ability to absorb or emit radiation
what are good absorbers and emitters of radiation?
dull black surfaces
what are poor absorbers and emitters of radiation?
shiny silver surfaces
how does surface temperature affect radiation emission?
higher surface temperature leads ton a higher rate of emission of radiation
how does the surface area of an object affect radiation emission and absorption?
objects with larger surface areas emit or absorb more heat per second compared to objects with smaller surface areas
what material should be used to keep something warm in a cooler environment?
shiny silver material
what material should be used to keep something cool in a warm environment?
a shiny silver material
how can a vacuum be used to reduce heat transfer?
placing a vacuum between silvered surfaces reduces heat loss through conduction and convection
how does a cap on a vacuum flask reduce heat loss?
it reduces heat loss through convection and evaporation
