Question

when does a thrown ball start to feel the force of gravity acting on it?
once the upward motion of the ball stops.
as soon as the ball reaches the peak in its trajectory.
as soon as the ball leaves the throwers hand.
it is always feeling the force of gravity on it.

Explanation:

Gravity is a force that acts on objects with mass near the Earth's surface at all times. When a ball is thrown, as long as it is in the Earth's gravitational field (which it is when near the Earth, like in the context of a thrown ball), the force of gravity acts on it. It's not dependent on the ball's motion state (e.g., upward motion, at peak, etc.). The only time - varying force is the force applied by the thrower when in contact with the ball. Once the ball is thrown (leaves the hand), the only constant force (neglecting air resistance in a basic physics analysis) is gravity. But in reality, even before being thrown (when just held), gravity acts on the ball. So, throughout its existence near the Earth (which is the case for a thrown ball in this context), gravity acts on it.

Answer:

It is always feeling the force of gravity on it.