Question 373601
One plane ate 520 feet is ascending at a rate of 40 feet per minute, while another plane at 3800 feet is descending at a rate of 120 feet per minute. How long will it take the two planes to be at the same altitude?
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Plane A 520 feet vertical rise 40 feet/min
plane B 3800 feet  vertical dip 120 feet per minute.
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This means that the vertically the speeds are 40 feet / minute & 120 feet /minute travelling towards each other.
so Add up the speeds
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120 + 40 = 160 feet per minute.
the distance between them = 3800 -520 =3280 feet
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t= d/r
3280/160

t = 20.5 minutes. they will be at the same altitude.

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m.ananth@hotmail.ca