The height h, in feet, of a projectile t seconds after launch is modeled by the equation h = 32t – 16t2. How long after launch does the projectile return to the ground?
a) 2 seconds
b) 4 seconds
c) 14 seconds
d) 16 seconds

Question

The height h, in feet, of a projectile t seconds after launch is modeled by the equation h = 32t – 16t2. How long after launch does the projectile return to the ground? 
a) 2 seconds
b) 4 seconds
c) 14 seconds
d) 16 seconds

anonymous · Answer

when it hits the ground, the height is 0...so if youplug in h=0 and solve the quadratic (using the quadratic formula) the answer (the positive valued answer) will be the time it hits the ground

anonymous · Answer

actually, you can factor the quadratic...no need to use the quadratic formula...

$$-16t^{2}+32t=0$$
$$t(-16t+32) = 0$$

anonymous · Answer

Thanks!