In a world where personal gravity fields can be adjusted with a device, Dax has set his gravity field to repel from the earth with a force equal to that of Earth's gravity. As a result, he hovers in place without moving up or down. Dax's friend, Jia, who is standing on the Earth's surface and doesn't have such a device, hands him a ball. What happens to the ball when Dax lets go of it? Respond briefly.
When Dax, who hovers due to his personal gravity field negating Earth's pull, receives the ball from Jia, the ball is initially under the influence of Earth's gravity, as it is not affected by Dax's personal device. The moment Dax lets go of the ball, it will be subjected to the standard Earth's gravity, as the ball itself is not equipped with any device to alter its own gravitational interaction. Therefore, once Dax releases the ball, the ball will fall to the ground, following the standard gravitational attraction towards the Earth that acts on all objects with mass that are not themselves generating an opposing gravitational field. This fall will occur because there is nothing to provide an upward force to counteract Earth's gravitational pull on the ball. Jia, observing from her vantage point on the ground, will see the ball drop and land on the Earth's surface following a downward trajectory.