How do you find the acceleration of you have from where it starts to a constant speed in a certain amount of time
for example: goes from 0 m/s to 10 m/s in 5.0s

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector inside a tv tube. the electron strikes the screen after traveling 26 cm horizontally and 19 cm vertically upward with no horizontal acceleration. what is the constant vertical acceleration provided by the deflector? (the effects of gravity can be ignored.)