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The height at which the atmosphere ceases to exist is about 80km. If the atmosph...


Question

The height at which the atmosphere ceases to exist is about 80km. If the atmospheric pressure on the ground level is 760mmHg, the pressure at a height of 20km above the ground level is

Options

A) 380mmHg

B) 570mmHg

C) 190mmHg

D) 480mmHg


The correct answer is B.

Explanation:

(p - 760)/(0 - 760) = (h - 0)/(80 - 0)
∴ (p - 760)/-760 = (20 - 0)/80
80(p-760) = -760(20-0)
∴80p - 60800 = -15200
80p = 60800 - 15200
80p = 45600
∴ p = 45600/80
p = 570mmHg

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Dicussion (1)

  • (p - 760)/(0 - 760) = (h - 0)/(80 - 0)
    ∴ (p - 760)/-760 = (20 - 0)/80
    80(p-760) = -760(20-0)
    ∴80p - 60800 = -15200
    80p = 60800 - 15200
    80p = 45600
    ∴ p = 45600/80
    p = 570mmHg

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