A projectile is launched from ground level at an angle of 50.0 degrees above the horizontal with a speed of 30.0 m/s. If the projectile is moving over level ground, how long is it in the air before it again contacts the ground

4.69 s

Explanation:

u = Initial velocity = 30 m/s

= Angle of launch =

g = Acceleration due to gravity =

Time taken by the projectile to land is given by

The time the projectile is in the air before it contacts the ground again is 4.69 s.

the part of the wave he is travelling on is the crest