A fairground ride has four carriages attached to a central vertical pole, as the plan view below shows. A motor turns the central pole about its axis, causing each of the four carriages to travel along a circular path. The distance from the centre of each carriage to the axis of the pole is $3.20\,\text{m}$. While moving, each carriage is acted on by an air resistance force of $85.0\,\text{N}$. Assume that no other significant resistive forces act. Which torque must the motor exert on the pole to maintain the system at constant maximum speed?
- A$5.44\,\text{N m}$
- B$272\,\text{N m}$
- C$544\,\text{N m}$
- D$1090\,\text{N m}$