Question

Ladenburg correction:
V_t = v(1+2.4 r/R).
This correction is due to wall effect only right??
Does v is the terminal velocity or the instantaneous velocity?? and if it is terminal how practically can i measure it without high-tech sensors(let's us say manually :d)?

Answer 1

1) Terminal velocity
2) a common experiment is to drop steel balls into graduated cylinders with glycerine.
3) the terminal velocity is determined by placing two pieces of tape a fixed distance apart
on the cylinder and measuring the time it takes to cover this distance.
4) The first piece of tape near the top is placed about 1 inch from the top of the glycerine
since it is expected that the terminal velocity is reached shortly after it enters the fluid.

Answer 2

Thanks i forgot that it's constant velocity :(