Question
An inclined plane making an angle of 30$^\circ$ with the horizontal is placed in a uniform horizontal electric field $200{N \over C}$ as shown in the figure. A body of mass 1 kg and charge 5 mC is allowed to slide down from rest at a height of 1 m. If the coefficient of friction is 0.2, find the time taken by the body to reach the bottom.
[g = 9.8 m/s2; $\sin 30^\circ = {1 \over 2}$; $\cos 30^\circ = {{\sqrt 3 } \over 2}$]