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System
A set of interconnected parts, the objects involved in doing the transfer of energy.
Open System
An open system exchanges matter and energy with its surroundings.
Closed System
A closed system exchanges only energy, but not matter, with its surroundings.
Isolated System
An isolated system cannot exchange matter or energy with the surroundings.
Heat
Transfer of thermal energy from one location to another.
Work
Movement of matter from one location to another, involved in the system.
1st Law of Thermodynamics
The total energy in a system remains constant, also known as the Law of Conservation of Energy.
Positive Work
Occurs when work done on the system increases heat and mechanical energy.
Negative Work
Occurs when work done on the system decreases heat and mechanical energy.
Perfect Machine
A theoretical machine where mechanical energy input equals mechanical energy output, no energy lost to friction.
2nd Law of Thermodynamics
Describes the direction of energy flow; heat naturally flows from hot to cold.
Heat Engine
Device that converts one form of energy into mechanical work, typically via combustion.
Internal Combustion Engine
Engine where fuel combustion takes place inside the working cylinder.
External Combustion Engine
Engine where fuel combustion occurs outside the working cylinder.
Heat Pump
Device that moves thermal energy in the opposite direction of spontaneous heat transfer.
Renewable Energy Sources
Energy sources that are continuously available and will not run out, e.g., solar, wind, hydro.
Non-Renewable Energy Sources
Energy sources that are limited and irreplaceable, e.g., fossil fuels, nuclear.
Efficiency
Measurement of how effectively a machine converts energy input to useful energy output.
Cogeneration
Process of using wasted energy from one process to power a second process.
Photosynthesis
Process used by plants to convert light energy into chemical energy.
Thermal Energy
Energy that comes from the temperature of matter, manifests in heat.
Mechanical Energy
The sum of potential energy and kinetic energy in a system.
Gravitational Potential Energy
Energy an object possesses due to its position in a gravitational field.
Kinetic Energy
Energy that an object has due to its motion.
Chemical Energy
Energy stored in the bonds of chemical compounds.
Efficiency Ratio
The ratio of useful output energy to total input energy, expressed as a percentage.
Mechanical Equivalent of Heat
Concept that heat can be converted to mechanical energy and vice-versa.
Thermal Pollution
Degradation of water quality by temperature increase due to human activities.
Greenhouse Gases
Gases, such as carbon dioxide, that trap heat in the atmosphere.
Non-renewable Resources
Resources that are consumed faster than they can naturally replenish.
Environmental Pollution
The introduction of harmful materials into the environment.
Energy Crisis
A situation where the demand for energy exceeds the supply.
Sustainable Society
A society that meets present needs without compromising future generations.
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