What happens to the jumper's acceleration when a basketball player jumps to make a shot, once the feet are off the floor?

It is "G", no more and no less. This question can be found on Physics tests. In this answer, g (also known as G-forces) is the amount of gravity exerted when one falls. This gravity is exerted by the Earth.

G comes from the word gravitation, which is used for various forces of acceleration including a steep turn, straight line, and dive. A G-force meter is used to measure "G". Fields such as engineering and science uses this measurement, which is specifically studied in plant and rocket science, as well as in studying race cars and engines.