Explanation:
The formula for the electric field produced by an infinite sheet of charge is outlined below.
E =
where,
is the surface charge density
Following this, the formula for the electric force acting on a proton is given as:
F = eE
where, e is the charge of a proton
According to Newton's second law of motion, the overall force on the proton can be expressed as follows.
F = ma
a = 
= 
= 
According to kinematic equations, the proton's speed in the perpendicular direction can be described as follows.

= 
= 
= 683.974 m/s
Thus, the overall speed of the proton can be calculated as follows.
v' =
=

= 
= 1178.73 m/s
Consequently, we conclude that the proton's speed is 1178.73 m/s.