Question 153474: A stone is thrown into a well with an intial speed of 8 feet per second. The well is 80 feet deep. How long will it take for the stone to hit the bottom of the well? Use the equation d=vt+16t^2. where d=depth of the well, v= initial speed, and time
choices:
1) 2
2) 5/2
3) 2 or 5/2
4) none of these
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A stone is thrown into a well with an intial speed of 8 feet per second. The well is 80 feet deep. How long will it take for the stone to hit the bottom of the well? Use the equation d=vt+16t^2. where d=depth of the well, v= initial speed, and time
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EQUATION:
d(t) = vt + 16t^2
80 = 8t + 16t^2
10 = t + 2t^2
2t^2 + t - 10 = 0
2t^2 + 5t - 4t - 10 = 0
t(2t+5) -2(2t+5) = 0
(2t+5)(t-2) = 0
Positive solution:
t = 2 seconds
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Cheers,
Stan H.
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choices:
1) 2
2) 5/2
3) 2 or 5/2
4) none of these
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