Question

When a soccer ball is kicked with a vertical speed of 25 m/s its height, h metres, after t seconds is given by the equation h=-5t^2+25t

a) how long after it is kicked is the soccer ball at a height of 30 m ?

b) How long is the soccer ball in the air?

Answer 1

a)h=30, solve for t
30=-5t^2+25t
5(t^2-5t+6)=0
5(t-3)(t-2)=0
t=2 (ball going up) or
t=3 (ball going down)

b) h=0, solve for t
0=-5t^2+25t
5t(5-t)=0
t=0 or t=5
Make similar interpretations.

Answer 2

dde