Answer:
The electrical power is 96.5 W/m^2
Explanation:
The energy balance is:
Ein-Eout=0
if:
Gsky=oTsky^4
Eb=oTs^4
qc=h(Ts-Tα)
if Gl≈El(l,5800)
lt= 2*5800=11600 um-K, at this value, F=0.941
The hemispherical emissivity is equal to:
lt=2*333=666 K, at this value, F=0
The hemispherical absorptivity is equal to:
Answer: The electric field decreases because of the insertion of the Teflon.
Explanation:
If the charge on the capacitor is held fixed, the electric field as a consequence of this charge distribution (directed from the positive charged plate to the negative charged one remains unchanged.
However, as the Teflon is a dielectric material, even though doesn't allow the free movement of the electrons as an answer to an applied electric field, it allows that the electrons be displaced from the equilibrium position, leaving a local negative-charged zone close to the posiitive plate of the capacitor, and an equal but opposite charged layer close to the negative plate.
In this way, a internal electric field is created, that opposes to the external one due to the capacitor, which overall effect is diminishing the total electric field, reducing the voltage between the plates, and increasing the capacitance proportionally to the dielectric constant of the Teflon.
Answer:
A safety manager is a person who designs and maintains the safety elements at workplace. A balance should be required for production and the job in providing work environment. As a safety officer in a medium sized manufacturing facility the following organizational system can be designed and maintained:
- Maintaining a workplace as per the guidelines by Occupational safety and health association. The rules and regulation should be such that maintains the manufacturing facilities.
- For warning to workers proper labelling, floor mapping, signs, posters should be used.
- Procurement and usage of safe tools.
- A guideline that describes safety standard and precautionary measures should be available to the workers. They should be aware about all the steps that needs to be taken in crisis.
- Ensuring that the workers have enough training safety and health or accident prevention.
- Identify and eliminate the hazardous elements from the workplace.
- A strict action should be taken against the worker in case of violation of rules and not adhering with guidelines.
Answer:
a) What is the surface temperature, in °C, after 400 s?
T (0,400 sec) = 800°C
b) Yes, the surface temperature is greater than the ignition temperature of oak (400°C) after 400 s
c) What is the temperature, in °C, 1 mm from the surface after 400 s?
T (1 mm, 400 sec) = 798.35°C
Explanation:
oak initial Temperature = 25°C = 298 K
oak exposed to gas of temp = 800°C = 1073 K
h = 20 W/m².K
From the book, Oak properties are e=545kg/m³ k=0.19w/m.k Cp=2385J/kg.k
Assume: Volume = 1 m³, and from energy balance the heat transfer is an unsteady state.
From energy balance: 
Initial temperature wall = 
Surface temperature = T
Gas exposed temperature = 
Answer:
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