After how many seconds does the ball hit the floor?

Question

The function  gives the height (in feet) of a ball dropped from the height of  after t seconds. A ball is dropped from a height of 8 feet. After how many seconds does the ball hit the floor?

Answer 1

The wording of the problem seems to say

h(t) = -16t² + 8,

with h in ft and t in sec. Set h(t) = 0 and solve for t.

-16t² + 8 = 0

16t² = 8

t² = 1/2

t = 1/√2 sec = (√2 / 2) sec

Note only the positive square root makes sense.