The electric field between two parallel plates is uniform, with magnitude $594\frac{N}{C}.$ A proton is held stationary at the positive plate, and an electron is held stationary at the negative plate. The plate separation is $3\mathrm{.}72cm.$ At the same moment, both particles'are released.

$($a$)$ Calculate the distance $($in $cm)$ from the positive plate at which the two pass each other. Ignore the electrical attraction between the proton and electron. $cm$

$($b$)$ Repeat part $($a$)$ for a sodium ion $(N{a}^{+})$and a chloride ion $(C{l}^{-}).($Give your answer in $cm.)$