Answer:
850.8480103 feet
Explanation:
First you take the diameter and find the circumference, which is (2)(pi)(r) plug in your r which is 26/2= 13 so 2(13)(pi) and multiply taht by 125 after that take your answer and divide by 12which is 850.8480103
Answer:
A selective surface with large absorption for solar radiation and high reflectance for thermal infrared radiation was produced by use of surface oxidation of stainless steel. The surfaces were studied for use with concentrated light in a solar power plant at temperatures of 400°C and higher.
In order to investigate the relation between surface treatment and optical properties, stainless steels (AISI 304 and 430) which were submitted to different chemical and mechanical surface treatments, were used. To increase the spectral selectivity, these surfaces were treated in air and in vacuum at different temperatures and times. The optical properties of these films were investigated. Visual and infrared spectral absorptances were measured at room temperature. The thermal hemispherical emittance and absorptance were obtained by a calorimetric method at 200°C. It was noticed that these chemically and mechanically treated stainless steel surfaces have good spectral properties without further oxidations. This is very important for high temperature uses. The best values are found for samples 7 and 8 under vacuum and air. These two samples with mechanically ground surfaces retained their selectivity and specularity after several hours oxidation. One can conclude that the surface ground treatment confers good selectivity on the steel surfaces for use in concentrating solar collectors with a working temperature of 500°C.
Sample surfaces were subjected to long temperature ageing tests in order to gain some idea of the thermal stability of the surfaces. The results promise better-performing surface and the production of durable selective finishes at, possibly, lower cost than competing processes.
Explanation:
Answer:
f = c / λ = wave speed c (m/s) / wavelength λ (m). The formula for time is: T (period) = 1 / f (frequency). λ = c / f = wave speed c (m/s) / frequency f (Hz). The unit hertz (Hz) was once called cps = cycles per second.
Explanation:
Answer:
a. population, units, sample
Explanation:
In a survey or in a research, population is defined as the total number of people or total number of items in the group that we want to study in a research. It is the entire pool from where a sample is drawn.
An unit is defined as the individual members for which the information or data is collected.
A sample is defined is defined as the group or part of the selection from where the information or data is to be obtained.
Answer:
gauge pressure is 133 kPa
Explanation:
given data
initial temperature T1 = 27°C = 300 K
gauge pressure = 300 kPa = 300 × 10³ Pa
atmospheric pressure = 1 atm
final temperature T2 = 77°C = 350 K
to find out
final pressure
solution
we know that gauge pressure is = absolute pressure - atmospheric pressure so
P (gauge ) = 300 × 10³ Pa - 1 × 
Pa
P (gauge ) = 2 × Pa
so from idea gas equation
................1
so 
P2 = 2.33 × Pa
so gauge pressure = absolute pressure - atmospheric pressure
gauge pressure = 2.33 × - 1.0 ×
gauge pressure = 1.33 × Pa
so gauge pressure is 133 kPa
