At the local radio controlled (RC) airfield, a 2.1 kg RC plane strikes a 1 kg aerial drone that is hovering stationary at an altitude of 11 m.

At the local radio controlled (RC) airfield, a 2.1 kg RC plane strikes a 1 kg aerial drone that is hovering stationary at an altitude of 11 m. Just after the collision, the two aircraft are stuck together and moving to the east at 8.3 m/s at an altitude of 11 m.

What is the speed (in m/s) of the plane just prior to the collision?