Energy
**Forms of Energy:**
– In a lightning strike, electric potential energy converts into light, sound, and thermal energy.
– Thermal energy involves microscopic matter constituents with kinetic and potential energy.
– Energy in a system can be potential, kinetic, or a mix of both.
– Mechanical energy combines translational and rotational kinetic and potential energy.
– Nuclear energy arises from atomic nucleus potentials due to nuclear or weak forces.
**Historical Development:**
– Leibniz introduced the concept of ‘vis viva’ in the 17th century.
– Émilie du Châtelet proposed the conservation of energy in the 18th century.
– Thomas Young first used the term ‘energy’ in 1807.
– Coriolis described kinetic energy in 1829, and Rankine coined potential energy in 1853.
– Joule discovered the link between mechanical work and heat generation in 1845.
**Units of Measure:**
– The joule is the SI unit of energy, named after James Prescott Joule.
– Energy can also be expressed in ergs, calories, British thermal units, and kilowatt-hours.
– The watt is the SI unit for energy rate, equivalent to one joule per second.
– Other units include the erg in CGS, foot pound in imperial units, and electronvolt.
– Work is defined as force times distance and is a function of energy.
**Conservation of Energy:**
– The law of conservation of energy states energy can’t be created or destroyed, only converted.
– Energy forms include kinetic, potential, chemical, radiant, and internal energy.
– Living organisms constantly exchange energy.
– Energy is essential for human civilization and is derived from various resources.
– The Earth’s climate and ecosystems are influenced by solar energy.
**Early Concepts:**
– Aristotle introduced the concept of ‘energeia’ in the 4th century BC.
– Leibniz proposed the concept of ‘vis viva’ in the late 17th century.
– The modern concept of kinetic energy was described by Coriolis in 1829.
– Rankine coined the term ‘potential energy’ in 1853.
– Joule discovered the link between mechanical work and heat generation in 1845.