- published: 30 Jun 2014
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In physics, energy (Greek: ἐνέργεια energeia "activity, operation") is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems. Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.
The total energy contained in an object is identified with its mass, and energy (like mass), cannot be created or destroyed. When matter (ordinary material particles) is changed into energy (such as energy of motion, or into radiation), the mass of the system does not change through the transformation process. However, there may be mechanistic limits as to how much of the matter in an object may be changed into other types of energy and thus into work, on other systems. Energy, like mass, is a scalar physical quantity. In the International System of Units (SI), energy is measured in joules, but in many fields other units, such as kilowatt-hours and kilocalories, are customary. All of these units translate to units of work, which is always defined in terms of forces and the distances that the forces act through.
Elon Musk (born June 28, 1971) is a South African-born American business magnate, engineer and inventor. He is best known for co-founding SpaceX, Tesla Motors and X.com, which later became Paypal after acquiring the service. He is currently the CEO and Chief Designer of SpaceX, CEO and Product Architect of Tesla Motors and Chairman of SolarCity. While at those companies, Musk co-designed the first viable electric car of the modern era, the Tesla Roadster, a private successor to the Space Shuttle, Falcon 9/Dragon, and the world's largest Internet payment system, PayPal.
Elon Musk was born in Pretoria, South Africa, the son of a Canadian-American mother and a South African father. His maternal grandfather was from Minnesota, and had moved to Saskatchewan, where Musk's mother was born. His father is an engineer and his mother is an author, nutritionist and model, appearing on the cover of New York Magazine in 2011 and a Time Magazine supplement in 2010.
Musk bought his first computer at age 10 and taught himself how to program; by the age of 12 he sold his first commercial software for about $500, a space game called Blastar.