Thermal physics

• Heat Capacity is the amount of energy needed to raise the temperature of a substance by 1 degree
• Specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree
• the equation for specific heat capacity is q = c x change in temperautre x mass
• the amount of heat energy required to raise the temperature of a substance by a certain amount is equal to the product of the substance’s heat capacity, its mass, and the change in temperature.
• Units for specific heat capacity joules per kilogram per degree Celsius. J/KgC
• thermal energy is the measure of internal energy of a thermodynamic system
• internal energy is sum of kinetic and potential energetic of the particles
• Assumptions of kinetic theory of gases:

  gases are composed of separate particles

  gas molecules are in constant, rapid, straight line motions.

  collions between molecules are complete elastic

  molecules of gas have no attraction or repulsion for each other

  each molecule in a gas has a different velocity
• brownian motion:

  random motion of particles of a fluid (liquids and gases)

  collisions of particles are due to random motion
• Pressure of gas:

  measure of amount of force created on walls of a container

  per unit area by gas particles collectively.

  pressure units:

  Nm-2 or Pa (pascals)
• volume of gas

  measure of space occupied by a gas in a container, usually volume of container is regarded as the volume of gas in it.

  units m3
• internal enemy is the sum of potential and kinetic energy of a thermodynamic system
• The variables which describe the current state of a thermodynamic system are called state variables
• state variables describe current state of a thermodynamic system relative to its previous state.
• a thermodynamic systems are classified on their interactions with their surrounding into open. closed and isolated systems.
• Boyles law: pressure and volume are inversely related to eachother, while temperature is kept constant. P is inversely proportional to 1 over V. PV=K
• Charles law:

  temperature and volume are directly related to each other while pressure is kept constant.

  V= KT
• lussacs law:

  change in pressure is directly related to change in temperature while volume remains constant.

  P=KT
• ideal gas equation

  p is directly proportional to t over v

  p = KT / v

  PV =KT

  PV= nRT

  r is ideal gas constant: 0.082

  n os number of moles
• 1. Thermal Energy: The total energy of particles in a system, including both kinetic and potential energy, measured in joules or calories.

  2. Heat Energy: The transfer of thermal energy from a hotter object to a cooler object due to a difference in temperature, measured in joules or calories.

  3. Temperature: A measure of the average kinetic energy of particles in a substance, indicating how hot or cold something is, measured in degrees Celsius or Kelvin.
• Latent heat is the heat absorbed or released when a substance changes its physical state completely at constant temperature
• Latent heat of fusion temperature remains constant as solid turn to liquid
• Latent heat of vaporization temperature remains constant as liquid turn to gas
• When a solid melts or liquid boils, energy must be added but the temperature remains constant considering the energy is used to break bonds
• specific latent heat of vaporisation is amount of heat required to evaporate one gram of a substance
• Specific latent heat of vaporisation (Lv) is the amount of energy required to change one kilogram of a substance from liquid to gas without changing the temperature
• Specific latent heat of fusion (Lf) is the amount of energy required to change one kilogram of a substance from solid to liquid without changing the temperature
• Q = mL

  L= Q / M

  latent heat is equal to heat energy over mass
• Boiling point is temperature at which internal pressure of a substance equals external pressure of atmosphere
• Melting point is point at which soils changes state to liquid during the phase of latent heat
• Conduction is the transfer of kinetic energy by means of vibrational motion of atoms or free electrons
• Convection is the transfer of kinetic energy by means of physical motion of particles
• Radiation is the transfer of heat energy by means of electromagnetic radiation
• Conduction happens in solid as the particles are tightly packed together and energy is transferred easily
• To stop convection you need to stop the free movement of fluids
• Radiation can travel through vacuums

  all objects absorb and emit radiation
• In faction heat is transferred via electromagnetic waves in the form of infrared radiation which is invisible to the eyes but can be felt as heat