Answer:
Acceleration,
Explanation:
Given that,
Electric field, E = 680 N/C
Speed of the proton, v = 1.3 Mm/s
We need to find the acceleration of the proton. We know that the force due to motion is balanced by the electric force as :

a and m are the acceleration and mass of the proton.



So, the acceleration of the proton is
. Hence, this is the required solution.