Find the total time of the shell

Question

an artillery shell is fired at an angle of 62.9 degrees above the horizontal ground with an initial speed of 1680 m/s. Acceleration of gravity is 9.8 m/s2. Neglect air resistance. Answer in units of min.

Answer 1

Let initial velocity be v=168m/s.  Angle θ = 62.9° 

v_y =v sin 62.9° = (168) (0.89)=149.6 m/s

Total time t= 2v_{y /g = 2(149.6)/9.8 = 50.5 s}