# A projectile is shot from the ground at a velocity of 25 m/s and at an angle of (5pi)/12. How long will it take for the projectile to land?

Jan 10, 2017

I got $5 s$ approx.

#### Explanation:

I tried to visualize the problem:

As you can see the projectile, along $y$, reaches the highest point, at height $h$, where its velocity will be zero. So we use equation $\left(2\right)$ and write:
$0 = 25 \sin \left(\frac{5}{12} \pi\right) - 9.8 \cdot t$
$t = 2.46 \approx 2.5 s$

This time will be repeated by the projectile to come down and impact on the ground, so, the total time of flight, $T$, of equation $\left(1\right)$ will then be:
$T = 2 t = 2 \cdot 2.5 = 5 s$