2.5 days to fall through a hole in the earth

Let’s say someone digs a hole through the centre of the earth, and back out the other side – a tunnel right the way through the planet. Now let’s say you decide to jump into that hole (not one of your best decisions, admittedly). It would take you around two and a half days of constant free fall until you pop out again from the hole on the opposite side. The physics underpinning this calculation are complex (for one thing, after the halfway mark you would theoretically be rising rather than falling), but the time is largely determined by air friction which prevents us falling any faster than 56 metres per second, otherwise known as terminal velocity.