Math: Word Problem
posted by Amy~ on .
A ball is thrown upward from the top of a building which is 96ft tall w/ Initial velocity of 80 ft per sec.
Distance s(ft) of ball from the ground after t sec is s=96+80t16t^(2)
1) how many sec. will the ball pass the top of the building when it is coming down?
How would I solve this?

set s(t) to 96 and solve.
96=96+80t16t^2
solve for t 
why would I set 96 for s(t) because that's the height of the building ?
but it's when the ball passes the top of the building
Also I tried solving it I got to
16t(t5)= 0 what should I do next 
I finished solving it. thank you

riddle: my ones number is double my tens number, I'am less than 70 and more than 60

A ball is thrown vertically upward with velocity 100ft/sec and height of building is 40ft what is maximum height reached by ball and what is velocity when ball hits the ground