Find electron's acceleration and final velocity

[404]

An electron has a mass of 9.1*10^-31 kg. Between the electrodes of a cathode-ray tube, it moves a distance of 4.0mm, accelerated by a net electrical force of 5.6*10^-15 N. Assuming it started by rest, find it's acceleration and final velocity.

I found the acceleration to be 6.15*10^15 m/s^2, which is confirmed by the answer book, but how can I get the final velocity without change in time? distance don't help at all if I don't know average velocity...

 

[Nx2]

u have accel, v1, and distance
use (v2)^2= (v1)^2 + 2ad

 

[OlderDan]

An electron has a mass of 9.1*10^-31 kg. Between the electrodes of a cathode-ray tube, it moves a distance of 4.0mm, accelerated by a net electrical force of 5.6*10^-15 N. Assuming it started by rest, find it's acceleration and final velocity.

I found the acceleration to be 6.15*10^15 m/s^2, which is confirmed by the answer book, but how can I get the final velocity without change in time? distance don't help at all if I don't know average velocity...

Force times distance in the direction of the force is work, and that equals change in kinetic energy.

Edit
OOPs.. two suggestions flying at the same time. They both lead to the same conclusion.

 

[404]

Ok I see, thanks.