A bullet is fired upward from ground level. Its height above the ground (in feet) at time t seconds is given by #H = -16t^2 + 1000t#. How many seconds does it take the bullet to return to ground level?

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Answer 1 · 2018-04-20T11:04:21

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You are looking for the moment when H will be 0 again. That is

#0=-16t^2+1000t=t(-16t+1000)#

this product will be zero if #t or (-16t+1000)# are zero

#t=0# is the initial state (when gun is fired)

#-16t+1000=0# give #-t=-1000/16=-62.5#. Thus #t=62.5# seconds