A cannon is mounted on a tower above a wide, level field. The barrel of the cannon is 20 m above the ground below. A cannonball is fired horizontally with an initial speed of 800 m / s. A cannon atop a castle tower fires a cannonball horizontally. Assuming air resistance can be neglected, approximately how long will the cannonball be in flight before it hits the ground

2.019 seconds.

Explanation:

Here we use the equation:

Distance covered = (initial speed x time) + 0.5 x (acceleration x time^2)

The vertical distance to cover is 20 meters.

Since the cannonball is fired horizontally, the initial vertical speed is 0 m/s.

Acceleration due to gravity is 9.81 m/s^2.

Substituting these values into the equation we get:

20 = (0 x time) + 0.5 x (9.81 x time^2)

Solving this equation for time gives us 2.019 seconds as the answer.