Explore BrainMass

Thermal Equilibrium

Thermal equilibrium in thermodynamics is used in two cases. The first is that of thermal equilibrium within a system for itself. The other case is that of a relation between the respective physical states of two bodies. Thermal equilibrium in a system for itself means that the temperature within the system is spatially and temporally uniform. Thermal equilibrium as a relation between the physical states of two bodies means that there is actual or implied thermal connection between them. Thermal equilibrium is concerned with the theory of temperature.

Heat can flow into or out of a closed system by way of thermal conduction or of thermal radiation to or from a thermal reservoir; when this process effects net transfer of heat, the system’s temperature can be changing. As the transfer of energy as heat continues, the system is not in thermal equilibrium.

When an isolated system is left long enough it will reach a state of thermal equilibrium in itself. The temperature will be uniform throughout but not necessarily a state of thermodynamic equilibrium if there is some structural barrier that can prevent some possible processes in the system from reaching equilibrium. 

Kyoto Box Optimization with the Sun at the Zenith

Please see attachment. I am having difficulty understanding what the optimal angle (theta) is. Kyoto box is a simple solar oven used extensively in Africa. Assuming a square box with four reflectors of L = 75 cm, on a sunny day with direct sunlight from the zenith, what is the optimum angle ϴ? What is the total solar power r

Physics: Fahrenheit, Celsius & Kelvin conversions; force to pump up a bicycle tire

Three thermometers are placed in a closet, insulated box and are allowed to reach thermal equilibrium. One is calibrated in Fahrenheit degrees, one in Celsius degrees, and one in Kelvins. The Celsius thermometer reads -40 degrees; Celsius and the Kelvin thermometer read 233K. Which of the following statements is necessarily tru

Consider two spin systems A and A' placed in an external field H.

I need to know how to start the problem, just how to do part a), and then I'll probably be able to do the rest on my own. Problem : Consider two spin systems A and A' placed in an external field H. System A consist of N weakly interacting localized particles of spin 1/2 and magntic moment u. Similarly, system A' consis

Einstein solids: macrostates and microstates

Consider a system of two Einstein solids, A and B, each containing 10 oscillators, sharing a total of 20 units of energy. Assume that the solids are weakly coupled, and that the total energy is fixed. (a) How many different macrostates are available to this system? (b) How many different microstates are available to th