An airplane, flying horizontally at an altitude of 3 miles, passes directly over an observer. If the constant speed of the air
plane is 240 miles per hour, how fast is its distance from the observer increasing 45 seconds later? Hint: Note that in 45 seconds (three fourths times StartFraction 1 Over 60 EndFraction equals StartFraction 1 Over 80 EndFraction hour ), the airplane goes 3 miles.
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Answer:
The answer is 4x³ + 6x²
<u>-TheUnknownScientist</u><u> 72</u>
The maximum amount of work performed is
Explanation:
The efficiency of a real heat engine is given by the equation:
(1)
where
is the temperature of the cold reservoir
is the temperature of the hot reservoir
However, the efficiency of a real heat engine can be also written as:
where
is the maximum work done
is the heat absorbed from the hot reservoir
can be written as
where
is the heat released to the cold reservoir
So the previous equation can be also written as
(2)
By combining eq.(1) and (2) we get
And re-arranging the equation and solving for , we find
Learn more about work and heat:
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