Energy
The mechanical work done by an external agent on a system is equal to the change in kinetic energy of the system:
- General work-energy theorem (translation and rotation)
The work done W by an external agent which exerts a force F (at r) and torque τ on an object along a curved path C is:
where θ is the angle of rotation about an axis defined by a unit vector n.
- Kinetic energy
- Elastic potential energy
For a stretched spring fixed at one end obeying Hooke's law:
where r2 and r1 are collinear coordinates of the free end of the spring, in the direction of the extension/compression, and k is the spring constant.
Read more about this topic: List Of Equations In Classical Mechanics
Famous quotes containing the word energy:
“Much of the modern resistance to chastity comes from men’s belief that they “own” their bodies—those vast and perilous estates, pulsating with the energy that made the worlds, in which they find themselves without their consent and from which they are ejected at the pleasure of Another!”
—C.S. (Clive Staples)
“A government deriving its energy from the will of the society, and operating, by the reason of its measures, on the understanding and interest of the society ... is the government for which philosophy has been searching and humanity been fighting from the most remote ages ... which it is the glory of America to have invented, and her unrivalled happiness to possess.”
—James Madison (1751–1836)
“Violence among young people ... is an aspect of their desire to create. They don’t know how to use their energy creatively so they do the opposite and destroy.”
—Anthony Burgess (b. 1917)