SOLUTION: At a hockey game, small foam hockey pucks are launched at a height of 2 m above the ice level by using a special sling shot. How long is a puck in the air if a student in the st

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: At a hockey game, small foam hockey pucks are launched at a height of 2 m above the ice level by using a special sling shot. How long is a puck in the air if a student in the st      Log On


   



Question 1047374: At a hockey game, small foam hockey pucks are launched at a height of 2 m above the ice level by using a
special sling shot. How long is a puck in the air if a student in the stands catches it on its way down 12 m above
the ice level? The model for the vertical motion of the puck can be approximated by the relation h=-5t^2+15t+2
, where is the time in seconds, and is the height in metres.

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
-5t^2+15t+2=12, and the longest time period is the value we want (there are two solutions)
-5t^2+15t-10=0
divide by -5
t^2-3t+2=0
(t-2)(t-1)=0
t=1,2 seconds.
t=2 seconds when it is on its way down at 12 meters above the ice.
graph%28300%2C300%2C-5%2C5%2C-10%2C20%2C-5x%5E2%2B15x%2B2%29