Story problem

Question

During her physics class, draconian throws a ball off the roof of her school. The height h of the ball in feet above ground is t seconds after she throws it is given h= -16t^2+24t+32

A. Find the height of ball 1/2 second after throws it

B. Find the time when the ball hits the ground, to the nearest tenth second.

Answer 1

A) Just plug 1/2 into the height equation at each value of t

 

h = -16(1/2)^2 + 24(1/2) + 32 = -16/4 + 12 + 32 = -4 + 12 + 32 = -4 + 44 = 40 feet

 

 

B) Set h = 0

 

0 = -16t^2 + 24t + 32

 

Now use the quadratic formula: 2 answers are obtained: 

-0.85078105935821217162205441865545331613010503315525472138 (throw out, negative)

 

 

2.350781059358212171622054418655453316130105033155254721382

 

2.4 seconds