A powered actuator slides a train door along a straight, horizontal track. The actuator exerts a constant force in the direction in which the door moves.
At the start of the movement, the front edge of the door is 0.18 m from one end of the track. The door slides away from this end. When it stops, its front edge is 1.08 m from the same end of the track.
The actuator does 135 J of work during this movement.
Calculate the force exerted by the actuator.