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Gravitational time dilation is a form of time dilation, an actual difference of elapsed time between two events, as measured by observers situated at varying distances from a gravitating mass. The lower the gravitational potential (the closer the clock is to the source of gravitation), the slower time passes, speeding up as the gravitational ...
where ˙ is the heat transferred per unit time, A is the area of the object, h is the heat transfer coefficient, T is the object's surface temperature, and T f is the fluid temperature. [8] The convective heat transfer coefficient is dependent upon the physical properties of the fluid and the physical situation.
The macroscopic energy equation for infinitesimal volume used in heat transfer analysis is [6] = +, ˙, where q is heat flux vector, −ρc p (∂T/∂t) is temporal change of internal energy (ρ is density, c p is specific heat capacity at constant pressure, T is temperature and t is time), and ˙ is the energy conversion to and from thermal ...
The flow of heat from Earth's interior to the surface is estimated at 47±2 terawatts (TW) [1] and comes from two main sources in roughly equal amounts: the radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of Earth. [2]
One can model particle diffusion by an equation involving either: the volumetric concentration of particles, denoted c, in the case of collective diffusion of a large number of particles, or; the probability density function associated with the position of a single particle, denoted P. In either case, one uses the heat equation
Heat transfer rate, or heat flow per unit time, is denoted by ˙, but it is not a time derivative of a function of state (which can also be written with the dot notation) since heat is not a function of state. [5] Heat flux is defined as rate of heat transfer per unit cross-sectional area (watts per square metre).
[3] [4] Heat refers to a quantity in transfer between systems, not to a property of any one system, or "contained" within it; on the other hand, internal energy and enthalpy are properties of a single system. Heat and work depend on the way in which an energy transfer occurs.
Most writers use it as a synonym for heat capacity, the ability of a body to store thermal energy. It is typically referred to by the symbol C th, and its SI unit is J/K or J/°C (which are equivalent). However: Christoph Reinhart at MIT describes thermal mass as its volume times its volumetric heat capacity. [1]