A. The initial speed in which the ball should be thrown is 27.65 m/s
B. The total time spent by the ball in the air is 5.64 s.
A. Determination of the initial velocity
v² = u² – 2gh (since the ball is going against gravity)
0² = u² – (2 × 9.8 × 39)
0 = u² – 764.4
Collect like terms
u² = 0 + 764.4
u² = 764.4
Take the square root of both side
u = √764.4
u = 27.65 m/s
B. Determination of the total time spent by the ball in the air.
We'll begin by calculating the time taken to reach the maximum height.
s = ½(u + v)t
39 = ½(27.65 + 0)t
39 = ½ × 27.6 × t
39 = 13.825 × t
Divide both side by 13.825
t = 39 / 13.825
t = 2.82 s
Finally, we shall determine the total time.
T = 2t
T = 2 × 2.82
T = 5.64 s
Therefore, the total time spent by the ball in the air is 5.64 s
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