Question

A stone is dropped from rest from an infinitely tall building. Compute its velocity after 2 seconds

Answer 1

Well, assuming the gravity still has a value, named "g" (although the building is infinitely tall and then its value should be zero), the velocity should be,

v=-gt

take t=2, and you have,

v=-2g

If you assume g=9.8 m/s^2, then,

v=-19.6 m/s.

But remember that physically there is no infinitely tall building.