A ball is thrown straight up into the air. At each of the following instants, is the ball's acceleration ay equal to g, - g, 0, g?

a = (-g) from the moment the ball is thrown, until it stops in the air.

a = (0) when the ball stops in the air.

a = (g) since the ball starts to fall.

Explanation:

The acceleration is (-g) from the moment the ball is thrown, until it stops in the air because the movement goes in the opposite direction to the force of gravity. In the instant when the ball stops in the air the acceleration is (0) because it temporarily stops moving. Then, since the ball starts to fall, the acceleration is (g) because the movement goes in the same direction of the force of gravity

Just after leaving your hand: - g

At the very top: g

Just before hitting the ground: g

Explanation:

A ball is thrown straight up into the air. At each of the following instants, is the ball's acceleration ay equal to g, - g, 0, g? a. Just after leaving your hand? b. At the very top (maximum height) ? c. Just before hitting the ground?

Remember that in physics when you use gravity as the acceleration fo an object it is negative when the object has a positive velocity or towards the sky and away form the center of the earth and gravity is positive when the objet is falling or going towards the center of the earth, acceleration can't be 0 when we are talinkg about gravity.