Final answer:
The initial vertical velocity (Vyo) of a football kicked with an initial velocity of 25 m/s at an angle of 40-degrees with the horizontal is approximately 16.07 m/s.
Step-by-step explanation:
The initial vertical velocity (Vyo) of a football kicked at an angle of 40-degrees with the horizontal is calculated using the sine component of the initial velocity. The equation to find Vyo is Vyo = Vo * sin(θ), where Vo is the initial velocity and θ is the angle of projection.
Given an initial velocity (Vo) of 25 m/s and an angle of 40 degrees, the initial vertical velocity would be:
Vyo = (25 m/s) * sin(40°) = (25 m/s) * 0.6428 ≈ 16.07 m/s.