Question

Please solve the above question

Answer 1

Understanding :

1) If the system is in equilibrium, then net torque about any point is 0.

2) About point O, there will be torques by Electric field force on +q and gravitational force on wheel centre.

Both these torques are opposite in direction.

Steps :
1) Take point O on base of wheel,
Make net torque 0 about that point.

2) Torque by Gravitational force will be
=> mg sin a R

Torque by Electric force will be qE cos a * 2R.


For Calculation see Pic.