Question 169835
An object launched upward with an initial velocity of 14.7 m/s from a height of 49 m will have a height of s(t)= -4.9t^2+49, where s is in meters and t is in seconds. How long will it take the object to hit the ground? 
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s(t) must be zero when the object hits the ground.
-4.9t^2+49 = 0
4.9t^2 = 49
t^2 = 49/4.9
Positive answer: 
t = sqrt(49/4.9)
t = 3.1622... seconds
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Cheers,
Stan H.