If you were to dig a hole through the Earth and jump into it, assuming there are no obstructions or factors like air resistance, you would initially fall towards the center of the Earth due to gravity. As you reach the center, gravity would gradually slow you down until you come to a stop.
However, due to momentum, you would not simply stop at the center. You would continue moving toward the other side of the Earth. As you move away from the center, gravity would start pulling you back, causing you to slow down and eventually come to a stop near the surface on the other side of the Earth.
At this point, the process would repeat in reverse. Gravity would then start pulling you back towards the center, and you would oscillate back and forth, passing through the center each time, with each oscillation gradually decreasing in amplitude due to energy loss from factors like friction and air resistance.
In theory, you would continue oscillating back and forth indefinitely, but in practice, factors such as air resistance and the Earth's rotation would eventually dampen the oscillations, causing you to come to a rest near the center.
It's important to note that this scenario assumes an idealized and simplified model, disregarding factors like air resistance, friction, heat generation, and the Earth's non-uniform density. In reality, such a journey through the Earth is not feasible, and attempting it would be extremely dangerous or impossible due to the extreme temperatures, pressures, and other geophysical factors encountered deep within the Earth.