Here's why:

* Thrust is a force that propels an object forward. It's most commonly associated with things like rockets and jet engines. Since the ball is thrown by hand, it doesn't have an internal engine generating thrust.

The forces acting on the ball in the air are:

* Gravity: This pulls the ball downwards.

* Air Resistance: This opposes the ball's motion and slows it down.

* Initial Force: This is the force you applied to the ball when you threw it, and it's only active for a brief moment.