Air resistance, friction both reduce velocity toward planet’s core
Falling down a hole through the center of the Earth would be rough — especially if there’s friction involved. A new study reveals what would happen to an intrepid traveler who jumped through a hypothetical tunnel through Earth, propelled by the force of gravity but impeded by the drag of air resistance and the friction of the tunnel walls.
Physicists have estimated that, if you jumped into a tunnel without such drag, you would be able to reach the other side in less than an hour. But include drag and it could be well over a year before you even reach Earth’s center — and you’d never make it to the other side — scientists report in a paper published online June 3 at arXiv.org.
“There’s a number of assumptions that you have to make to solve this problem,” says physicist Alex Klotz of MIT, who was not involved in the new study. To simplify the calculations, scientists have