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Power in mechanical systems is the combination of forces and movement. In particular, power is the product of a force on an object and the object's velocity, or the product of a torque on a shaft and the shaft's angular velocity. Mechanical power is also described as the time derivative of work.
The Stefan–Boltzmann law gives the power emitted per unit area of the emitting body, = (,) Note that the cosine appears because black bodies are Lambertian (i.e. they obey Lambert's cosine law ), meaning that the intensity observed along the sphere will be the actual intensity times the cosine of the zenith angle.
In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area, per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m 2 ); kg/s 3 in SI base units .
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal n̂, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
Sound power or acoustic power is the rate at which sound energy is emitted, reflected, transmitted or received, per unit time. [1] It is defined [2] as "through a surface, the product of the sound pressure, and the component of the particle velocity, at a point on the surface in the direction normal to the surface, integrated over that surface."
The input power provided by the cyclist is equal to the product of angular speed (i.e. the number of pedal revolutions per minute times 2π) and the torque at the spindle of the bicycle's crankset. The bicycle's drivetrain transmits the input power to the road wheel , which in turn conveys the received power to the road as the output power of ...
tech: the power the Z machine reaches in 1 billionth of a second when it is fired [citation needed] 3 × 10 14: weather: Hurricane Katrina's rate of release of latent heat energy into the air. [48] 3 × 10 14: tech: power reached by the extremely high-power Hercules laser from the University of Michigan. [citation needed] 4.6 × 10 14
In physics and many other areas of science and engineering the intensity or flux of radiant energy is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. [a] In the SI system, it has units watts per square metre (W/m 2), or kg⋅s −3 in base units.