Two identical balls , each having a charge `q` and mass `m` , are suspended from a common point by two insultating strings each of length `L`. The balls are held at a separation `x` and then released. Find
(a) the electric force on each ball
(b) the component of the resultant force on a ball along and perpendicular to string
(c ) the tension in the string
(d) the acceleration of one of the balls. Consider the situation only for the instant just after the release.

Explanation

(a) Electric force between balls , `F_(e ) = (1)/(4 pi in_(0)) (q^(2))/(x^(2))`
(b) Resolving forces along and `_|_^(ar)` to string.
Resultant force on ball along the string,
`T - (mg cos theta + F_(e ) sin theta ) = 0` { the string is unstrechable}
`_|_^(ar)` to string `= | F_(e ) cos theta - mg sin theta|`
`theta` can be obtained from geometry.
( c) Since the net force on the ball along string is zero , hence
`T = mg cos theta + F_( e) sin theta`
(d) Acceleration of ball `a = (|F_(e ) cos theta - mg sin theta|)/(m)`