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:
“The scholar may be sure that he writes the tougher truth for the calluses on his palms. They give firmness to the sentence. Indeed, the mind never makes a great and successful effort, without a corresponding energy of the body.”
—Henry David Thoreau (18171862)
“A great number of the disappointments and mishaps of the troubled world are the direct result of literature and the allied arts. It is our belief that no human being who devotes his life and energy to the manufacture of fantasies can be anything but fundamentally inadequate”
—Christopher Hampton (b. 1946)
“After the planet becomes theirs, many millions of years will have to pass before a beetle particularly loved by God, at the end of its calculations will find written on a sheet of paper in letters of fire that energy is equal to the mass multiplied by the square of the velocity of light. The new kings of the world will live tranquilly for a long time, confining themselves to devouring each other and being parasites among each other on a cottage industry scale.”
—Primo Levi (19191987)