Thermal physics Flashcards
If one object is hotter than another then there is a
net flow of thermal energy from the hotter one to the colder one
When two objects are in thermal equilibrium
there is no net flow of thermal energy between them
In order to measure temperature a scale is needed with
two fixed points at defined temperatures
What are the issues with the Celsius scale?
The fixed points, freezing and boiling points, can vary significantly depending on the surrounding atmospheric pressure
What is the SI unit for temperature?
Kelvin
What fixed defined temperature points does the absolute temperature scale use?
absolute zero and the triple point of pure water
How are the atoms and molecules arranged in a solid?
arranged regularly and packed closely together with strong electrostatic forces of attraction between them holding them in fixed positions but they can vibrate so they have kinetic energy
How are the atoms and molecules in a liquid arranged?
Still very close together but have more kinetic energy than those in a solid, they can flow past each other
How are the atoms and molecules in a gas arranged?
Have more kinetic energy than those of a liquid ad are much further apart. They are free to move past each other due to negligible electrostatic forces between them. They move randomly with different speeds and in random drections
What are the five ideal gas assumptions?
The gas contains a very large number of atoms or molecules moving in random directions with random speeds
The atoms or molecules of the gas occupy a negligible volume compared with the volume of the gas
The collisions of atoms or molecules with eachother and the container walls are perfectly elastic
The time of collisions between the atoms or molecules is negligible compared to the time between collisions
Electrostatic forces between atoms or molecules are negligible except during collisions
define internal energy
the sum of the randomly distributed kinetic and potential energies of atoms or molecules within a substance
