Dear expert, dear all. As my knowledge, the single phase motor is not a seft-starting motor. i suppose that there is only main winding in single phase motor. as you know, the rotor can not start because of the 2 opposites force cause by 2 oppositely rotating magnetic fields. the question is that : 1. Why we give the 1 phase motor an external force in either direction , the motor will start to run ? ( i think the motor only run for short time until this force run out , because it always exist 2 opposites force when the main winding of stator have power supply. like we turn the wheel by hand ) 2. with a normal single phase motor ( starting winding with a capacitor and main winding ) what is the cause can make the speed of the motor increase because the capacitor and the starting winding only give it the constant force in the starting period, and why we cut out the starting winding , the motor continue increase speed to the rated speed while there is only 1 main winding which have cause the 2 same opposites force ? Forgive me if my eng is not good and it is a stupid question, thank in advance.