Thermal Physics Flashcards
Energy transfer between two objects happens when:
- One object does the work on the other object (it extact force from the other and make its move)
- By heating due to the temperature difference between two objects (conduction, convection, or radiation)
What is the internal energy of an object?
- The sum of the ramdom distribution of the kinetic and potential energies of its molecules.
- Is the energy of its molecules due to their individual movements and positions.
Internal energy of an object due to its temperature can be called:
Thermal energy.
Internal energy of an object increases because:
- Energy transfer by heating
or - Work done on the object (ex. electricity)
Internal energy of an object is constant when:
- There is no energy transfer (by heating or work done)
or - Energy transfer balance with each other (heating or work done)
First Law of Thermodynamics
- The change of internal energy = the total energy transfer due to work done and heating.
- Energy can only be converted, never created or destroy
- The work done by an object is transferred by heating.
- The directions of the energies transfer are very important (determine increase or decrease of the object’s internal energy)
What is a molecule?
- Is the smallest part of a pure substance. - Is made by atoms (ex. water= +2 hydrogen +1 oxygen)
What is an atom?
- The smallest part of an element characteristic of that element
- (ex. hydrogen = a proton and an electron).
What happens to the molecule when the temperature increases?
1- Molecules vibrate vibrate more.
2- Increases its kinetic energy.
3- After a limit, it will change its state (solid-liquid-gas).
Characteristics of arregement in the three states:
- States: Solid -> Liquid -> Gas
- The particles are always the same, only the arregemet of the particles, the forces between them, the empty space between them, and the speed are different.
- Matter is made up of particles
- Particles and make up matter are constantly in motion
- Particles have empty spaces between them that contain nothing
- ## Particles attrac each other
Charasteristics of solids:
- Particles are closely arrenged
- Particles do not move around but vibrate on their fixed position
- Paricles have small spaces between them
- The forces of attraction between the particles are very strong and hold them together
Charasteristics of liquids:
- Particles are losely arrenged but close together
- Particles move around quiet fast and slide pass each other.
- Paricles have small spaces between them but larger than in a solid.
- The forces of attraction between the particles are weaker, so the particles are not held together and move around.
Charasteristics of gas:
- Particles are not arrenged in any particular way.
- Particles move around much faster than liquid (they move ramndonly).
- Paricles the biggest spaces between them.
- The forces of attraction are extremely weak, so they move freely
Thermal equilibrium
- Two objects at the same temperature.
- There is no transfer by heating
Celsius scale
- Unit: °C
- 0° = Ice point
- 100 ° = Steam point
Absulute scale (Kelvin scale)
- Unit: Kelvin “K”
- Absolute zero:
- Lowest possible temperature
- 273.15 K, also known as triple point, is where ice, water and vapour coexist. - There is no knowledge of any substance reaching 0 K
Formula for Celcius and Kelvins
Temperature in °C = absolute temperature in kelvins -273.15
