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Question

An object is dropped from 34 feet below the tip of the pinnacle atop a 934-ft tall building. The height h of the object after t seconds is given by the equation h=-16^2 + 900. Find how many seconds pass before the object reaches the ground

Answer 1

If the equation of the height is given by

 

h=-16t²+900

 

You would replace "h" with the height when it reaches the ground, which is 0.

 

0 = -16 t² +900

 

Subtract 900 from both sides.

 

-900 = -16 t²

 

Divide both sides by -16

 

56.25 = t²

 

Take the square root of both sides to find t.

 

7.5 = t

 

 

Final answer:  It took 7.5 seconds to reach the ground.