To enhance heat rejection from a spacecraft, an engineer proposes to attach an array of rectangular fins to the outer surface of
1 answer:
Answer:
Attached below is the required diagram related to the question
answer :
q'3 = WбT^4
engineer's proposal has merit
Explanation:
Let : A'3 represent the deep space
A'1 represent the surface area , F13 and F23 represent the view factors
T1 , T2, T3 ; represent temperatures
q'3 represent net rate of heat radiation
Derive the expression for the rate per unit length at which radiation is transferred from the surfaces to deep space
derived expression ; q'3 = WбT^4
attached below is a detailed solution
Given that The emission is proportional to the area of the opening and the surfaces ( 1 and 2 ) have the same temperature hence this problem can be treated as a two surface enclosure. hence the engineer's proposal have merit .
attached below is a prove ( b )
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Answer:
13.5 ms
Explanation:
The sound wave travels with uniform motion in both cases, so the time taken to cover a distance d is given by:
where
d is the distance to cover
v = 340 m/s is the speed of sound in air
So for the people across the newsroom,
d = 4.7 m
So the time taken is
The radio waves instead travels with uniform motion at the speed of light:
So the time taken for them is
where
d = 82 km = 82,000 m
is the distance of the people who are 82 km away. Substituting,
Therefore, the difference in time is