(Kinetic Energy) - Evette Taylor


The energy abody has by virtue of its motion is called Kinetic Energy. If the body's mass is m and its velocity is v, its kinetic energy is

Kinetic energy +KE=1/2mv2 (Beiser,pg 36)


History of Kinetic Energy


The adjective kinetic has its roots in the Greek word κίνησις (kinesis) meaning motion, which is the same root as in the word cinema, referring to motion pictures.

The principle in classical mechanics that E ∝ mv² was first developed by Gottfried Leibniz and Johann Bernoulli, who described kinetic energy as the living force, vis viva. Willem 's Gravesande of the Netherlands provided experimental evidence of this relationship. By dropping weights from different heights into a block of clay, 's Gravesande determined that their penetration depth was proportional to the square of their impact speed. Émilie du Châtelet recognized the implications of the experiment and published an explanation.[[#cite_note-2|[]][[#cite_note-2|3]][[#cite_note-2|]]]

The terms kinetic energy and work in their present scientific meanings date back to the mid-19th century. Early understandings of these ideas can be attributed to Gaspard-Gustave Coriolis, who in 1829 published the paper titled Du Calcul de l'Effet des Machines outlining the mathematics of kinetic energy. William Thomson, later Lord Kelvin, is given the credit for coining the term "kinetic energy" c. 1849–51.[[#cite_note-3|[]][[#cite_note-3|4]][[#cite_note-3|]]][[#cite_note-4|[]][[#cite_note-4|5]][[#cite_note-4|]]]

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Application of Kinetic Energy


The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. When they start rising, the kinetic energy begins to be converted to gravitational potiential energy. The sum of kinetic and potential energy in the system remains constant, assuming negligible losses to friction.
Spacecraft use chemical energy to take off and gain considerable kinetic energy to reach orbital velocity. This kinetic energy gained during launch will remain constant while in orbit because there is almost no friction. However, it becomes apparent at re-entry when the kinetic energy is converted to heat.

Kinetic energy can be passed from one object to another. In the game of billiards, the player gives kinetic energy to the cue ball by striking it with the cue stick. If the cue ball collides with another ball, it will slow down dramatically and the ball it collided with will accelerate to a speed as the kinetic energy is passed on to it. Collisions in billiards are effectively elastic collisions, where kinetic energy is preserved.

Flywheels are being developed as a method of energy storage.This illustrates that kinetic energy can also be rotational.(New World Encyclopedia, Vol.Pg)


References

  1. Beiser, A. (1988). Physical Science (2nd Edition). New York, NY: McGraw Hill
  2. http://en.wikipedia.org/wiki/Kinetic_Energy, retrieved August 10,2011
  3. Kinetic energy. (2009, February 26). New World Encyclopedia.

This WikiPage developed by (Evette Taylor - 2011 SU)