SOLUTION: A ball is dropped from the top of a 256-foor cliff. The height of the stone about the ground t seconds after being dropped is h = 16t2 + 256 in feet. Find the amount of time it tak
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Question 1188744: A ball is dropped from the top of a 256-foor cliff. The height of the stone about the ground t seconds after being dropped is h = 16t2 + 256 in feet. Find the amount of time it takes for the stone to hit the ground. Answer by ikleyn(52780) (Show Source):
In your post, the equation for the height is written INCORRECTLY.
The correct form is h = -16t^2 + 256 feet.
Find time "t" from this quadratic equation
-16t^2 + 256 = 0 (level of the ground)
To solve, factor the equation
-16(t^2 - 16) = 0
to make its root clearly visible t^2 = 16, = - = 4, = = 4.
Of the two roots, only positive t = 4 works as the solution to the problem.
ANSWER. 4 seconds.
Solved.
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