Is there any way to modifled an AC motor to use DC power supply to operate?

 

You would need to build or buy an inverter to take the DC and convert it into an AC voltage @ frequency that was compatible with the motor.

AC motors do not normally have brushes like DC motors do. AC motors in general are very simple, reliable, efficient, and designed to operate at a fixed speed by being supplied with a fixed frequency AC voltage.

 

Is there any way to modifled an AC motor to use DC power supply to operate?

If it is a universal motor you can power it by DC supply as well as AC. Check it.

 

This might sound like an uneducated question, but what is the main difference between an AC and DC motor?

 

I saw in one of the other posts that someone wanted touse a bycicle dynamo to charge a battery. So it is safe to assume tht the dynamo is supplying AC an not DC?

 

That should be a generator, and it will output pulsating DC.