A soccer ball is kicked into the air from level ground with an initial speed of 20 m/s and returns to ground level at which angle above the horizontal should the ball be kicked in order for the ball to travel the greatest total horizontal distance

For the ball to travel the greatest distance it must be kicked at an angle of 45° to the horizontal

Since 90° is upward 0° is straightforward 45° splits at the middle to give the greatest distance

Explanation:

What is the maximum range of a projectile?

The range (R) of the projectile is the horizontal distance it travels during the motion.

The reason that 45 degrees is the best launch angle (resulting in the longest flight) is that it perfectly splits the upward and forward forces. Ninety degrees is straight up. Zero degrees is straight forward. 45 degrees is right in the middle, half of 90.