A hovercraft of mass 69.0 kg can move on a horizontal surface, the x-y plane. A single unbalanced force acts on the hovercraft, but the size of the force is unknown. The hovercraft initially has a velocity of 6.0 m/s in the positive x direction and some time later has a velocity of 9.0 m/s in the positive y direction. How much work is done on the hovercraft by the force during this time?