SOLUTION: The equation (((h=-16^2-32t+320))), gives the height of a ball, thrown downward from the top of a 320ft building with an initial velocity of 32ft/sec. Find the time it takes for th

Question 30016: The equation (((h=-16^2-32t+320))), gives the height of a ball, thrown downward from the top of a 320ft building with an initial velocity of 32ft/sec. Find the time it takes for the ball to reach a height 160ft. Heres what I have so far, h=160, 160=16t^2+32t+320,160=0,16t^2+32t-320=0,divide by 16,
leaving t^2+2t-20, using the quadratic formula t=b(+or-)radical sign (-2)^2-4(1)(20)/2=0, 2(+or-)radical sign 4+80/2, so the answer I get is 2+ radical sign,84/2, and 2- radical sign 84/2. My math book says the answer is 2.317seconds, but does not show how to get there. Thanks,

Answer by Cintchr(481) (Show Source): You can put this solution on YOUR website!
I see your first mistake ...
subtract 160 from both sides
You left it as 320
simple little mistakes like that will kill you.
divide by 16
use the quadratic ...

divide by 2
assuming ONLY the possitive root ...
root out 11 = 3.31662 ......

rounded to the nearest thousandth
RELATED QUESTIONS
The equation h=-16t^2-32t+320 gives the height od a ball, thrown downward from the top of (answered by Nate)

The equation h=-16t^2-32t+320 Give the height of a ball, thrown donward from top of a... (answered by checkley71)

The equation (((h=-16^2-32t+320))), gives the height of a ball, thrown downward from the... (answered by Cintchr)

h=-16t^2-32t+320 gives the height of a ball thrown downward from the top of a 320 foot... (answered by Alan3354)

I need to understand each step in the procedure to show and explain EACH step in setting... (answered by Nate)

I am really having troubles with these word problems. the equation -16t^2 - 32t +... (answered by josmiceli)

A building is 48 ft. tall. From the top of this building a ball is thrown straight up... (answered by funmath)

Elena throws a ball into the air from a building. The equation h= -16t^2 +32t+48 gives... (answered by Alan3354)

A ball is thrown downward from the top of a 180 foot building with an initial velocity of (answered by richwmiller)