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Answer:
C) 2.2 seconds
Step-by-step explanation:
The initial vertical speed of the football is ...
v = (18.0 m/s)sin(36.9°) ≈ 10.807 m/s
Since the ball starts and ends at ground level, its speed when it hits the ground is the same as its launch speed. That is, the acceleration due to gravity causes the velocity to change from +v to -v. The time required to do that is ...
t = 2v/g = 2(10.807 m/s)/(9.8 m/s^2) = 21.614/9.8 s ≈ 2.206 s
The football is in the air about 2.2 seconds.
