How long is the ball in the air?

Question

h=-16^2+120t models the height h, in feet, of the ball after t seconds. How long is the ball in the air? 

Answer 1

Hi Leah,

 

The ball will be in the air until the height equals 0.

 

So, set h = 0 and solve

 

0 = -16t² + 120t

 

0 = t(-16t+120)

 

so when t is 0 the ball will be at height 0  but that is not the solution we want

 

so

 

0 = -16t + 120

 

16t = 120

 

t = 7.5 seconds 

 

Hope this helps