Answer: 5/2 or 2.5 seconds
Step-by-step explanation:
When the ball hits the ground, the height is 0. We can set the equation equal to 0 to find how long it takes to hit the ground.
You didn't include time in your equation, I will assume the equation is h(t)=-16t²+32t+20. If not, let me know and I will fix it.
-16t²+32t+20=0
-4(4t²-8t-5)=0
4t²-8t-5=0
t=5/2 and t=-1/2 [quadratic formula]
We know our time cannot be t=-1/2 because you can't have negative time. Therefore, our time is t=5/2 or 2.5 seconds.
