# A projectile is shot from the ground at a velocity of 19 m/s and at an angle of (pi)/2. How long will it take for the projectile to land?

The projectile takes $3.87 s$ to land.
In this particular case there is only the vertical component of motion (because angle is 90°). We consider the equation $s = v t - \frac{1}{2} a {t}^{2}$ and assume $s = 0$. So $t \left(v - \frac{1}{2} a t\right) = 0$ and $t = 2 \frac{v}{g} = \frac{2 \cdot 19 \frac{m}{s}}{9.81 \frac{m}{s} ^ 2} = 3.87 s .$