Question

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?

Answer 1

I got `5s` 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 `(2)` and write:
`0=25sin(5/12pi)-9.8*t`
`t=2.46~~2.5s`

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 `(1)` will then be:
`T=2t=2*2.5=5s`