Neither do I know how it is called exactly, but squared is on degree higher polynomial then linear.
Exponential would mean that for step (say 20Amps) the current in the motor increases the heat is doubled, so if at 40Amps the waste heat is 60Watts then at 60Amps it is 120Watts, at 80Amps its is 240Watts and at 120Amps the heat is a scorching 960Watts.
Sorry jmcb1984
Aha. Thanks for the correction.