Electric potential

i guess the spheres r concentric
if it is so,

sphere A will have potential due to spheres A,B,C n value will be:
(kq1\a)+(kq2\b)+(kq3\c)...............(1)

similarly sphere B will be having potential due to A,B,C

(kq1\b)+(kq2\b)+(kq3\c)

{since,the point is outside the sphere A,thus charge on A behave as point charge

n also the point is inside C thus potential at that point is as same as on the surface of C

now for c;
(kQ1\c)+(kq2\c)+(kq3\c).................(2)

i m not so sure abt second ans but i did it dis way:

as the sphere A is grounded thus the net chrge on A becomes:
-a[(q2\b)+(q3\c)] from eqn 1

on substituting the values in eqn 2

we get potential on C as:

kq2[1\c-1\b]

n so net reduction is

(kq1\c)+(kq2\b)+(kq3\c)

is this correct

plzzzzzzzzzzzzzzzz telll

part (i) is correct but part (ii) is wrong..

Two +ve point charges. each of magnitude q,are fixed on the points y=+a and y=-a.Suppose a positively charged particle of the charge q' and mass m is displaced slightly 4m the origin in the direction of the axis. .. . then find out a) What is its speed at infinity? b)If the particle is projected toward the left along the x-axis from a point at a large distance to the right of the origin, with a velocity half that acquired in part (a), at what distance from the origin will it come to rest?? (c) If a negatively charged particle were released from rest on the x-axis, at a very large distance to the left of the origin, what would be its velocity as it passed the origin??