A particle having mass m, charge $q$ is projected with velocity $v_0$ along y- axis in a region of uniform magnetic field $B_0$  which is outward and perpendicular to the plane of the paper as shown in the figure. The particle is continuously subjected to a frictional force which varies with velocity as ${\overrightarrow{F}}_r=-\alpha \overrightarrow{V}$, where $\alpha$ is a constant. Consequently the particle moves on a spiral path till it comes to rest at point P. The x-co-ordinate of point P is $5K.$ Find K? 
(Take $\alpha ={10}^{-3}kg/s; q={10}^{-3}C; B_0=1T, v_0=1m/s, m=20gm$)