Thread: Another velocity Problem

If a ball is thrown vertically upward with a velocity of 80 ft./s, then its height after t seconds is s = 80t-16t^2.

a) What is the velocity of the ball when it is 96 feet above the ground on its way up? On its way down?

I already found in another part of this question that the maximum height is 100 ft. However I think for this I need to set up an inequality, but of what?

80-32t>96
-96 -96
-16(2t+1) > 0

t > (-1/2) ???????


80-32t<96


t < (-1/2) ???????


I have tried some things but I cant' seem to get any further...

Originally Posted by qbkr21

If a ball is thrown vertically upward with a velocity of 80 ft./s, then its height after t seconds is s = 80t-16t^2.

a) What is the velocity of the ball when it is 96 feet above the ground on its way up? On its way down?

I already found in another part of this question that the maximum height is 100 ft. However I think for this I need to set up an inequality, but of what?

80-32t>96
-96 -96
-16(2t+1) > 0

t > (-1/2) ???????


80-32t<96


t < (-1/2) ???????


I have tried some things but I cant' seem to get any further...

put s = 96 in the original question and solve for t.

then plug that t into the velocity function to find the velocity at that time.

Originally Posted by qbkr21

If a ball is thrown vertically upward with a velocity of 80 ft./s, then its height after t seconds is s = 80t-16t^2.

a) What is the velocity of the ball when it is 96 feet above the ground on its way up? On its way down?

I already found in another part of this question that the maximum height is 100 ft. However I think for this I need to set up an inequality, but of what?

80-32t>96
-96 -96
-16(2t+1) > 0

t > (-1/2) ???????


80-32t<96


t < (-1/2) ???????


I have tried some things but I cant' seem to get any further...

what does "on its way down" mean? the instant it starts to fall? if so, the velocity is zero then

I take it that the 16 is on the way up and the -16 is on the way down?

Originally Posted by qbkr21

I take it that the 16 is on the way up and the -16 is on the way down?

yup, that's right. i guess that's what they mean by on its way down. they mean on its way down when it's at 96 feet.

Jhevon you are super-Super-Cali-Fragalistitc-Expi-Ali-Docious!!!!!!!!!!!!

Originally Posted by qbkr21

Jhevon you are super-Super-Cali-Fragalistitc-Expi-Ali-Docious!!!!!!!!!!!!

o stop it