According to a file i downloaded the re-140Ra-2270 motor has a nominal voltage of 1.5 volts and no-load current of 0.21 amps, does that mean the internal resistance of a re-140ra-2270 motor is 7.14 ohms?

 

Not exactly. The resistance is best measured with an ohm meter while the motor is unpowered and stationary. That will determine its stall current. Is the stall current specified?
The no load current will also be dependent on the generated back EMF as well as the resistance. So the Impedance of the motor is pretty complex, and depends on the speed of rotation along with the resistance, inductance and back EMF. It is beyond my math ability to calculate.

 

Stall current is specified. Stall current is 2.1 amps. So internal resistance of re-140ra-2270 is 0.714 ohm?

 

That is what I would think.

 

So, if the stall current is 2.1 amps, then you would think, internal resistance of motor is 0.714 ohm?

 

So, if the stall current is 2.1 amps, then you would think, internal resistance of motor is 0.714 ohm?

Yes, but if it stays stalled for any length of time it will heat up and the resistance will increase.