Question 428730
If a ball is thrown straight up with an initial velocity of 64 feet per second, it's height after t seconds is given by h=-16tsquared + 64t. How long will it take for the ball to hit the ground?
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Given:
h=-16t^2 + 64t
Since h represents the height and the ground is zero -- set h to zero and solve for t:
0=-16t^2 + 64t
0=-t^2 + 4t
0=t(-t + 4)
t = {0, 4}
We can throw out the 0 solution leaving
t = 4 seconds