# physics

posted by
**Chris**
.

electrons are accelerated from rest over a distance of 800m to a velocity of 3x10 7 m/s. what is the acceleration of the electrons and what formula did you use to find the acceleration.

(1/2)[V(final)^2 - V(initial)^2] = a X

V(final) = sqrt (2 a X)

a = [V(final)^2/(2 X)]

=5.63*10^11 m/s^2

thank you, I was trying to start with finding the time first and couldn't figure it out. I tried changing the average velocity formula to come up with t. t=change in displacement / velocity, but wasn't sure if that was a proper way to change the formula, definitely didn't come up with the same answer. thanks.

Your method should have also worked. The distance covered is Vaverage = Vfinal/2 = a T/2.

Vaverage* T = X

Now eliminate T

Vaverage = (a/2)*(X/Vaverage)

Vaverage^2 = (a/2) X

Vfinal^2 = 2 a X