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| In ], '''kinetic energy''' is ] possessed by a body by virtue of its ]. |
In ], '''kinetic energy''' is ] possessed by a body by virtue of its ]. In ], a body with ] ''m'', moving in a straight line with velocity ''v'', has a ''translational kinetic energy'' of | ||
| :<math> E_k = \frac{1}{2} m v^2 </math>. | :<math> E_k = \frac{1}{2} m v^2 </math>. | ||
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| If a body is rotating, its ''rotational kinetic energy'' equals ''I''ω<sup>2</sup>/2, where ''I'' is its ] and ω its ]. | If a body is rotating, its ''rotational kinetic energy'' equals ''I''ω<sup>2</sup>/2, where ''I'' is its ] and ω its ]. | ||
| In ]'s ], the kinetic energy of a body is | |||
| <math>(m - m_0)c^2</math> | |||
| where m is its total mass, m<sub>0</sub> is its mass (or rest mass), and c is the ] in vaccuum. Relativity theory states that the total mass of an object grows towards infinity as its velocity approaches the speed of light, and thus that it is impossible to accelerate an object beyond this boundary. | |||
| Where gravity is weak, and objects move at much slower velocities than light (e.g. in everyday phenomena on Earth), Newton's formula is an excellent approximation of relativistic kinetic energy. | |||
| See also: | See also: | ||
Revision as of 14:47, 25 September 2003
In physics, kinetic energy is energy possessed by a body by virtue of its motion. In Newtonian mechanics, a body with mass m, moving in a straight line with velocity v, has a translational kinetic energy of
- .
.If a body is rotating, its rotational kinetic energy equals Iω/2, where I is its moment of inertia and ω its angular velocity.
In Einstein's relativistic mechanics, the kinetic energy of a body is
where m is its total mass, m0 is its mass (or rest mass), and c is the speed of light in vaccuum. Relativity theory states that the total mass of an object grows towards infinity as its velocity approaches the speed of light, and thus that it is impossible to accelerate an object beyond this boundary.
Where gravity is weak, and objects move at much slower velocities than light (e.g. in everyday phenomena on Earth), Newton's formula is an excellent approximation of relativistic kinetic energy.
See also: