Question 234421
use 4.9t^2 + vot = s 

a coin is tossed downward with an initial velocity of 30 meters per second(v0)at an altitude of 402 meters(s). approximately how long does it take the coin to reach the ground?
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-4.9t^2-30t = -402 meters
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4.9t^2 + 30t -402 = 0
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Use Quadratic formula:
t = [-30 +- sqrt(900 - 4*4.9*-402)]/(9.8)
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t = [-30 +- sqrt(8779.2)]/9.8
Positive solution:
t = [-30+93.7]/9.2
t = 6.924 seconds
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Cheers,
Stan H.