the roof is 25 feet high. the function. how many seconds does it take for the hammer to hit the ground? the function h+-16x^2+25

Question

i dont get it lol. 

Answer 1

if the hammer is dropped from the roof, which is 25 feet above the ground, then y = -16t^2 + 25, where the origin is at ground level, and where y is the distance of the hammer above the ground at t seconds --- when the hammer hits the ground, at t = T seconds, we have that y = 0 --- in which case, 0 = -16T^2 + 25, or 16T^2 = 25, or T^2 = 25/16, or T = 5/4 seconds = 1.25 seconds