# Charged particle moving under electric field

**1. The problem statement, all variables and given/known data**

A charged particle having charge q and mass m is projected into a region of uniform electric field of strength E, with velocity v perpendicular to E. Throughout the motion apart from electric force particle also experiences a dissipative force of constant magnitude qE and directed opposite to its velocity. If |v|=6 m/s, then find its speed when it has turned through an angle of 90.

**3. The attempt at a solution**

The trajectory of the particle will be a curved path. Work done by dissipative force = ΔK.E.

[itex]qEx=\dfrac{1}{2} m(v_f ^2 – v^2) [/itex]

But how do I find the path length traversed by the particle? It would be helpful if someone could guide me.

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