# Three Laws of Thermodynamics

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Science
Subject:
Physics
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Three Laws of Thermodynamics

First Law- Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. The First Law of Thermodynamics (Conservation) states that energy is always conserved, it cannot be created or destroyed. In essence, energy can be converted from one form into another.

Second Law- states that "in all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state." This is also commonly referred to as entropy. A watchspring-driven watch will run until the potential energy in the spring is converted, and not again until energy is reapplied to the spring to rewind it. A car that has run out of gas will not run again until you walk 10 miles to a gas station and refuel the car. Once the potential energy locked in carbohydrates is converted into kinetic energy (energy in use or motion), the organism will get no more until energy is input again. In the process of energy transfer, some energy will dissipate as heat. Entropy is a measure of disorder: cells are NOT disordered and so have low entropy. The flow of energy maintains order and life. Entropy wins when organisms cease to take in energy and die.

Third Law- states that as the temperature approaches absolute zero (0 K), the entropy of a system approaches a constant (and minimum) value. The entropy of a perfect crystalline state is zero at 0 K. In this way, the third law provides an absolute reference point for the determination of entropy of any substance. The third law also says that it is not possible for any system to reach absolute zero in a finite number of steps. This effectively makes it impossible to ever attain a temperature of exactly 0 K

Thermodynamics- the branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy.Absolute Zero- the lowest temperature that is theoretically possible, at which the motion of particles that constitutes heat would be minimal. It is zero on the Kelvin scale, equivalent to –273.15°C or –459.67°F.Entropy- a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system.Temperature- the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.Heat- the quality of being hot; high temperatureCalorie- the energy needed to raise the temperature of 1 gram of water through 1 °C (now usually defined as 4.1868 joules).Energy- the strength and vitality required for sustained physical or mental activityPE ( potential energy)- the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.KE (kinetic energy)- energy that a body possesses by virtue of being in motion.Exothermic- (of a reaction or process) accompanied by the release of heat.Endothermic- (of a reaction or process) accompanied by or requiring the absorption of heat.Thermal Expansion- is the tendency of matter to change in volume in response to a change in temperature, through heat transfer. Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, the kinetic energy of its molecules increases.Thermal Contraction- is the decrease in the volume of a substance caused by cooling. Cooling causes particles to slow down. this causes the. kinetic energy. to go down.Radiation- the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.Convection- the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.Conduction- the process by which heat or electricity is directly transmitted through a substance when there is a difference of temperature or of electrical potential between adjoining regions, without movement of the material.