[Mark_Heli (Mark)]

I was just thinking about black holes and had two questions to try and help visualise the distance & speed of an incoming particle on a human understandable scale:

1. What is the "vertical distance" that an incoming particle would have to travel to get from a diameter of 25km down to 1mm, and then the plank length?

2. How long it would take for the incoming particle to travel these two distances?

Hopefully the attached picture help to explain these questions clearly...

Thanks,
Mark