Complete question is;
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?
Answer:
2 seconds
Explanation:
We are told that the height function is given by;
h = 32t – 16t²
Now, the velocity will be the derivative of the height equation.
Thus;
v(t) = dh/dt = 32 - 32t
Now, for projectiles, at max height, v = 0.
Thus;
32 - 32t = 0
32t = 32
t = 32/32
t = 1 s
It will take the same time it took to get to Max height as it will to get to ground from that height.
Thus, total height = 1 + 1 = 2 seconds