Final answer:
The direction of a ball's acceleration during flight is downward due to gravity. In the case of a ball pushed east to west, the horizontal acceleration is westward. For an airplane landing traveling east, the acceleration is westward, which is negative deceleration.
Step-by-step explanation:
During the flight of a ball, its acceleration is downward due to the force of gravity. This is true regardless of the ball's horizontal motion; gravity acts continuously on the ball, pulling it towards the Earth. A ball that is pushed from east to west will accelerate in the same direction as the push, meaning westward, as per Newton's Second Law of Motion. However, this refers specifically to horizontal acceleration. Vertically, the acceleration due to gravity is always downward and is constant in magnitude. When an airplane lands traveling east, its acceleration is toward the west, which is considered negative if you take east as positive, indicating that it is decelerating.