Answer:
For this system to be efficient, the surfaces above the luminous ceiling must be white, so that all the light been transmitted is reflected.
Explanation:
White surfaces reflect light at almost 100% efficiency, this ensures that non of the light been transmitted is absorbed.
Thus, if one type of illumination system consists of rows of strip fluorescents and a ceiling that will transmit light. For this system to be efficient, the surfaces above the luminous ceiling must be white so that all the light been transmitted is reflected.
Ice. The formation of ice in the myriad of tiny cracks and joints in a rock's surface slowly pries it apart over thousands of years. Frost wedging results when the formation of ice widens and deepens the cracks, breaking off pieces and slabs. Frost wedging is most effective in those climates that have many cycles of freezing and thawing. Frost heaving is the process by which rocks are lifted vertically from soil by the formation of ice. Water freezes first under rock fragments and boulders in the soil; the repeated freezing and thawing of ice gradually pushes the rocks to the surface.
Answer:
at constant pressure, the heat flow for any process is equal to the change in the internal energy of the system plus the PV work done. Comparing the previous two equations shows that at constant pressure, the change in the enthalpy of a system is equal to the heat flow: ΔH=qp.
Explanation:
Give brainliest
Answer:
Step 1
Given
Diameter of circular grill, D = 0.3m
Distance between the coal bricks and the steaks, L = 0.2m
Temperatures of the hot coal bricks, T₁ = 950k
Temperatures of the steaks, T₂ = 5°c
Explanation:
See attached images for steps 2, 3, 4 and 5
Answer:
a)
, b)
, c) ![T = 200.829\,^{\textdegree}F](https://tex.z-dn.net/?f=T%20%3D%20200.829%5C%2C%5E%7B%5Ctextdegree%7DF)
Explanation:
a) The tank can be modelled by the Principle of Mass Conservation:
![\dot m_{1} + \dot m_{2} - \dot m_{3} = 0](https://tex.z-dn.net/?f=%5Cdot%20m_%7B1%7D%20%2B%20%5Cdot%20m_%7B2%7D%20-%20%5Cdot%20m_%7B3%7D%20%3D%200)
The mass flow rate exiting the tank is:
![\dot m_{3} = \dot m_{1} + \dot m_{2}](https://tex.z-dn.net/?f=%5Cdot%20m_%7B3%7D%20%3D%20%5Cdot%20m_%7B1%7D%20%2B%20%5Cdot%20m_%7B2%7D)
![\dot m_{3} = 125\,\frac{lbm}{s} + 10\,\frac{lbm}{s}](https://tex.z-dn.net/?f=%5Cdot%20m_%7B3%7D%20%3D%20125%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D%20%2B%2010%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D)
![\dot m_{3} = 135\,\frac{lbm}{s}](https://tex.z-dn.net/?f=%5Cdot%20m_%7B3%7D%20%3D%20135%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D)
b) An expression for the specific enthalpy at outlet is derived from the First Law of Thermodynamics:
![\dot m_{1}\cdot h_{1} + \dot m_{2} \cdot h_{2} - \dot m_{3}\cdot h_{3} = 0](https://tex.z-dn.net/?f=%5Cdot%20m_%7B1%7D%5Ccdot%20h_%7B1%7D%20%2B%20%5Cdot%20m_%7B2%7D%20%5Ccdot%20h_%7B2%7D%20-%20%5Cdot%20m_%7B3%7D%5Ccdot%20h_%7B3%7D%20%3D%200)
![h_{3} = \frac{\dot m_{1}\cdot h_{1}+\dot m_{2}\cdot h_{2}}{\dot m_{3}}](https://tex.z-dn.net/?f=h_%7B3%7D%20%3D%20%5Cfrac%7B%5Cdot%20m_%7B1%7D%5Ccdot%20h_%7B1%7D%2B%5Cdot%20m_%7B2%7D%5Ccdot%20h_%7B2%7D%7D%7B%5Cdot%20m_%7B3%7D%7D)
Properties of water are obtained from tables:
![h_{1}=180.16\,\frac{BTU}{lbm}](https://tex.z-dn.net/?f=h_%7B1%7D%3D180.16%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D)
![h_{2}=28.08\,\frac{BTU}{lbm} + \left(0.01604\,\frac{ft^{3}}{lbm}\right)\cdot (14.7\,psia-0.25638\,psia)](https://tex.z-dn.net/?f=h_%7B2%7D%3D28.08%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D%20%2B%20%5Cleft%280.01604%5C%2C%5Cfrac%7Bft%5E%7B3%7D%7D%7Blbm%7D%5Cright%29%5Ccdot%20%2814.7%5C%2Cpsia-0.25638%5C%2Cpsia%29)
![h_{2}=29.032\,\frac{BTU}{lbm}](https://tex.z-dn.net/?f=h_%7B2%7D%3D29.032%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D)
The specific enthalpy at outlet is:
![h_{3}=\frac{(125\,\frac{lbm}{s} )\cdot (180.16\,\frac{BTU}{lbm} )+(10\,\frac{lbm}{s} )\cdot (29.032\,\frac{BTU}{lbm} )}{135\,\frac{lbm}{s} }](https://tex.z-dn.net/?f=h_%7B3%7D%3D%5Cfrac%7B%28125%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D%20%29%5Ccdot%20%28180.16%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D%20%29%2B%2810%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D%20%29%5Ccdot%20%2829.032%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D%20%29%7D%7B135%5C%2C%5Cfrac%7Blbm%7D%7Bs%7D%20%7D)
![h_{3}=168.965\,\frac{BTU}{lbm}](https://tex.z-dn.net/?f=h_%7B3%7D%3D168.965%5C%2C%5Cfrac%7BBTU%7D%7Blbm%7D)
c) After a quick interpolation from data availables on water tables, the final temperature is:
![T = 200.829\,^{\textdegree}F](https://tex.z-dn.net/?f=T%20%3D%20200.829%5C%2C%5E%7B%5Ctextdegree%7DF)