A charged particle having mass m I projected in a uniform electric field with a kinetic energy `K_(0)`. After time `t_(0)` it was observed that the kinetic enrgy of the particle was `(K_(0))/(4)` and its velocity was perpendicular to the field.
(a). (a) How much more time is required for the particle to regain its lost kinetic energy? (b) Write the impulse of the electric force acting on the particle between the two points where its kinetic energy is `K_0`. Neglect all other forces on the particle apart from the electrostatic force.

Answer

(a). `t_(0)`
(b). `sqrt(6mK_(0))`