A Ball Is Thrown

Question

A ball is thrown downward from a window in a tall building. Its position at the time (t) in seconds is s=16t²+32t, where is is in feet. How long (to the nearest tenth) will it take the ball to fall 261 feet?

Answer 1

 

 

16t^2 + 32t = 261

 

16t^2 + 32t - 261 = 0

 

t = [-32 +or- sqrt( 32*32 + 4*16*261) ]/32

 

t = 3.16083

 

 

 

 

 

 

Answer 2

Set s(t) = 261 and solve for t.

 

16t² + 32t = 261

 

16t² + 32t - 261 = 0

 

t ≅ 3.2 or -5.2 s

 

Since time is positive,

 

t = 3.2 s