A ball is thrown downward from the top of a 180 foot building with an initial velocity of 24 feet per second. The height of the ball in h in feet after t seconds given by the equation h=-16t^2-24t+180. How long after the ball is thrown will it strike the ground?



Answer :

Answer:

  2.687 seconds

Step-by-step explanation:

You want to know how long it takes a ball to hit the ground if its height is given by h = -16t² -24t +180.

Time

The ball will hit the ground when the height is zero:

  0 = -16t² -24t +180

  0 = t² +1.5t -11.25 . . . . . . divide by -16

  0 = (t +.75)² -11.8125 . . . . complete the square

  t +0.75 = √11.8125 . . . . . add 11.8125 and take the square root

  t = -0.75 +√11.8125 ≈ 2.68693

The ball will hit the ground about 2.687 seconds after it is thrown.

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Additional comment

Only the positive answer is relevant in this problem.

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