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Homework Statement
An electron with speed 2.0E7 m/s is traveling parallel to a uniform electric field of magnitude 1.18E4 N/C. How far will the electron travel before it stops? How much time will elapse before it returns to its starting point
q = 1.60E-19 C
mass of electron = 9.11E-31 kg
velocity (initial) = 2.10E7 m/s
velocity(final) = 0 (zero)
Homework Equations
Electric Field
E=F/q --> F=qE
Acceleration / Force equation
a=F/m
Constant Acceleration
v(final)^2=v(initial)^2 +2a*(delta x) --> delta x = (v(final)^2 - v(initial)^2) / 2a
The Attempt at a Solution
F=qE = (1.60E-19 C)(1.8E4 N/C) = 2.88E-15N
a=F/m = (2.88E-15N) / (9.11E-31 kg) = 3.16E15 m/s^2
delta x = (v(final)^2 - v(initial)^2) / 2a
delta x = (0 - 2.10E7 m/s) / 2*(3.16E15 m/s^2)
delta x = -6.97785E-2 m <--- ACCORDING TO MASTERING PHYSICS THIS ANSWER IS WRONG!
with the 2nd part of the question... I was going to use the equation
delta x = 1/2[v(initial) + v(final)]*t
but since my delta x is wrong, i haven't quite started this part...
Any and all help will be appreciated! Thank you in advance!