No! It's a secret.Can i know why?
It seems to me that you need to be given a description, from which you can deduce this assumption. In the absence of such information, I would take the statement as a given assumption.My textbook says motion of electron in an electric field is similar to projectile motion. In projectile motion, we assume the initial velocity to be zero for the following cases
1) When the body starts from rest
2) If a body is dropped from a height.
But i can't correlate why the initial velocity is zero for an electron in its upward direction.
The knowledge that initial velocity is zero tells you that the momentum is zero in that direction and tells you nothing about the position in that direction.Thanks steveb and davebee.
@steveb: Can i presume since the initial velocity is zero in vertical upward direction, the position or momentum can't be determined accurately in that direction?