Answer:
122.17 m/s
Step-by-step explanation:
x cos 40 = horizontal velocity
1500 m / x cos 40 = time in the air = 1958.11 / x
x sin 40 = vertical velocity
find when shell vertical velocity = 0 (this is max height....1/2 way through its flight) , the time when it hits the ground will be twice this...
0 = x sin 40 - 9.8 t
t = x sin40 / 9.8 time in the air is twice this = .13118 x
Equate the two times from above to solve for x
1958.11/ x = .13118 x
x = 122.17 m/s