Lesson 1: Summary

Lesson 1: Summary

• Internal energy is the total energy contained within a system, comprising both internal kinetic energy (due to molecular motion) and internal potential energy (due to molecular attractive forces).
• Heat, on the other hand, is the energy in transit between bodies resulting from a temperature difference.
• Thermodynamic work refers to the energy transfer between systems, which can be mechanical or thermal in nature.
• Heat and temperature, while related, are distinct concepts.
• Heat is a process variable indicating energy transfer, whereas
• temperature is a fundamental physical quantity that measures the average kinetic energy of particles.
• Heat is not a property of an object; it is the energy crossing the boundary of a system due to temperature differences.
• Temperature changes result from the transfer of heat energy.
• Heat energy flows from hotter to cooler bodies until thermal equilibrium is reached, where temperatures equalize.
• The measurement of heat transfer is called calorimetry, conducted using a calorimeter.
• The SI unit of heat energy is the joule (J).
• According to the first law of thermodynamics, the heat involved in a process is the difference between the system’s final and initial states.
• Heat and work are interchangeable forms of energy transfer.
• Heat increases a substance’s internal energy, while work involves mechanical energy transfer. For example, heating a gas in a closed system increases its temperature and internal energy.
• For example, heating a gas in a closed system increases its temperature and internal energy, potentially doing work by moving a piston.
• Thermal equilibrium in thermodynamics occurs when two systems have the same temperature, signifying no net heat flow between them.