Posted by **Pat** on Tuesday, November 3, 2009 at 9:42pm.

If a ball is thrown vertically upward with a velocity of 160 ft/s, then its height after t seconds is s = 160t - 16t2.

What is the velocity of the ball when it is 96 ft above the ground on its way up? (Consider up to be the positive direction. Round the answer to one decimal place.)

What is the velocity of the ball when it is 96 ft above the ground on its way down? (Round the answer to one decimal place.)

- Calc -
**Pat**, Tuesday, November 3, 2009 at 9:43pm
*Revised*

If a ball is thrown vertically upward with a velocity of 160 ft/s, then its height after t seconds is s = 160t - 16t^2.

What is the velocity of the ball when it is 96 ft above the ground on its way up? (Consider up to be the positive direction. Round the answer to one decimal place.)

What is the velocity of the ball when it is 96 ft above the ground on its way down? (Round the answer to one decimal place.)

- Calc -
**bobpursley**, Tuesday, November 3, 2009 at 9:44pm
velocity= ds/dt= 160-32t

use the s formula to find t (you get two t, a quadratic) when s=96

then put those times in the velocity equation above.

- Calc -
**Pat**, Tuesday, November 3, 2009 at 9:58pm
that is what i am having trouble with =/

i got 96= 160t-16t^2 and i dont know how to factor. so i tried -16t^2+160t-96 and used the quadratic formula and i got two answer: .6 and 9.4...i do not know what i am doing wrong, but i really need help finding t when it's 96 feet.

Thank you.

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