A particle of mass `10^-3 kg` and charge `5 muC` is thrown at a speed `20 ms^-1` against a uniform electric field of strength `2xx 10^5 NC^-1`, How much distance will it travel before coming to rest momentarily?

Explanation

Mass =` m = 10^(-3) kg`
Charge = `q = 5 muC = 5 xx 10^(-6)C`
Initial speed = `u = 20 ms^(-1)`
Final speed = `v = 0`
Electric field = `E = 2 xx 10^5 NC^(-1)`
Since the particle is thrown against the electric field, so acceleration produced in it is
`a = - F/m = - (qE)/(m)`
`a = - (5 xx 10^(-6) xx 2 xx 10^5)/(10^(-3))`
`a = - 10^(3) ms^(-2)`
Using the relation , `v^2 - u^2 = 2 aS` we have
`(0)^2 - (20)^2 = 2(-10^3) S`
`S = (400)/(2 xx 10^3) = (400)/(2000) = 1/5 = 0.2m`
So distance covered by the particle before fi coming to rest momentiarly =`S = 0.2 m `