An automatic sliding door accelerates as it begins to open. The motor receives electrical energy during this stage. The measured energy transfers are shown in the table.
| Electrical energy supplied to the motor | Increase in the kinetic energy store of the door | Energy transferred by friction to the thermal stores of the tracks and rollers | Energy carried away by sound |
|---|---|---|---|
| 20.0 J | 4.5 J | 7.0 J | 1.0 J |
Electrical resistance also transfers energy to the thermal store of the motor windings.
Calculate the energy transferred to the thermal store of the motor windings.