Answer:
the speed of the proton is 
Explanation:
Generally Electric potential energy resulting from a proton can be mathematically represented as

Where
R is the radius of the disc which is given as 
q is the charge on the proton with a value of 
the mass of this proton has a value of 
z is the distance of the center of the disk from the question



According the law of conservation of energy
The change in kinetic energy of the proton + change in electrostatic = 0
potential energy
The change in kinetic energy is 
Since u = 0 the equation becomes
change in electrostatic potential energy is 
Substituting this into the equation we have
Recalling that
we have
Substituting values 
Making v the subject

