SOLUTION: Time in the air. A ball is tossed into the air from a height of 12 feet at 16 ft/sec. How long does it take to reach the earth?

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Question 197687: Time in the air. A ball is tossed into the air from a height
of 12 feet at 16 ft/sec. How long does it take to reach the
earth?

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Time in the air.
A ball is tossed into the air from a height of 12 feet at 16 ft/sec.
How long does it take to reach the earth?
:
The equation: -16t^2 + 16t + 12 = h
where
-16t^2 = gravity pulling down
+16t = initial velocity upward
12 = initial height when ball is tossed
h = height in feet
:
h = 0 when it strikes the ground
:
-16t^2 + 16t + 12 = 0
Use the quadratic formula:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In this problem x = t; a=-16; b=+16; c=12
t+=+%28-16+%2B-+sqrt%2816%5E2+-+4+%2A+-16+%2A+12+%29%29%2F%282%2A-16%29+
:
t+=+%28-16+%2B-+sqrt%28256+-+%28-728%29+%29%29%2F%28-32%29+
:
t+=+%28-16+%2B-+sqrt%28256+%2B+768+%29%29%2F%28-32%29+
;
t+=+%28-16+%2B-+sqrt%281024+%29%29%2F%28-32%29+
The positive solution
t+=+%28-16+-+32%29%2F%28-32%29+
t = %28-48%29%2F%28-32%29
t = +1.5 seconds to strike the earth