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# A ballet dancer is practicing a leap from the stage to an upper deck. If her initial velocity as she leaps is 18 feet per second, how long is she in the air

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A ballet dancer is practicing a leap from the stage to an upper deck. If her initial velocity as she leaps is 18 feet per second, how long is she in the air before she lands on the deck, 5 feet above the lower deck? Use h= -16t^2+18t

Grace_for_Mom  Mar 16, 2017
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She jumps and initially PASSES the 5 ft deck and comes back down to it:

5 = -16t^2 + 18t

16t^2 - 18t + 5 = 0     use quadratic formula to find t = 20/32  or  16/32

Since she jumps so quickly initially she jumps PAST 5ft (@ 16/32 sec) and comes back down to the 5 ft level at 20/32 sec

ElectricPavlov  Mar 16, 2017
edited by ElectricPavlov  Mar 16, 2017

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