Heat, work, and energy

• Work - Measure of energy transfer that occurs when an object is moved over a distance by an external force
• Energy - The ability to do work. Forms of energy are mechanical, electric, nuclear, and thermal energy.
• Thermal Energy - The energy contained within a system that is responsible for its temperature. Kinetic energy of moving particles of matter, measured by their temperature. It is different from heat although has an important relation.
• Heat - The transfer of thermal energy between substances.
• Temperature - The measure of hotness or coldness expressed in terms of any of several scales, including Fahrenheit and Celsius
• Thermodynamics - Science of the relationship between heat, work,

  temperature, and energy. In broad terms,

  thermodynamics deals with the transfer of energy from

  one place to another and from one form to another
• System - A quantity of matter or a region in space that is of interest.
• Surrounding - The mass or region outside the system is called the surroundings.
• Boundary - A closed, 3D surface that encloses the system and separates it from its surroundings.
• Three types of systems:

  • Open system
  • Closed system
  • Isolated system
• Isolated system - A system that is not influenced in any way by the surroundings.
• Closed system - has no transfer of mass with its surroundings, but may have a transfer of energy (either heat or work) with its surroundings.
• Open system - may have a transfer of both mass and energy with its surroundings.
• Three types of heat transfers:

  • Conduction
  • Radiation
  • Convection
• Heat transfer - Process in which the molecules are moved from the region of higher temperature to lower temperature.
• Heat - Represented by the letter ‘Q’. Energy caused by temperature difference. The amount of internal energy entering or leaving a system.
• Heat is measured in Joules (J)
• Thermal equilibrium - Systems (or objects are said to be in thermal equilibrium of there is no net flow of thermal energy from one to the other. If two objects are in thermal equilibrium, they are at the same temperature.
• Spontaneous process - A process which occurs without any external input to the system.
• Non-spotaneous process - Will not take place unless it is “driven” by the continual input of energy from an external source
• The heat pump - Heat pumps compress cold ambient air and, in so doing, heat it to room temperature
• Work - Energy caused by physical motion. Represented by ‘W
• Isothermal processes – system's temperature remains constant.
• Isobaric processes - system's pressure does not change.
• Isochoric processes - system's volume does not change.
• Adiabatic processes - no heat is transferred to or from the system.
• Internal energy or thermal energy - It is measured in Joules (J) and is represented by ‘U’. Sum of random translational, rotational and vibrational kinetic energies