A fluid, contained in a horizontal cylinder fitted with a frictionless leakproof piston, is continuously agitated by means of stirrer passing through the cylinder cover. The cylinder diameter is 0.40 m. During the stirring process lasting 10 minutes, the piston slowly moves out a distance of 0.485 m against the atmosphere. The net work done by the fluid during the process is 2 kJ. The speed of the electric motor driving the stirrer is 840 r.p.m. Determine the torque in the shaft and the power output of the motor.