Two people are in a robot on a river. The current of the river water carries them at a speed of 5 m/s even when they are not rowing what will happen to the boats motion of no other force acts on the boat.

Answer 1

If the two people in the robot (boat) are not rowing and no other forces are acting on the boat, the boat will simply drift downstream with the current of the river at a speed of 5 m/s.

Since the current is a consistent force acting on the boat, it will continue to move in the direction of the current at that speed until the people start rowing or another force acts on it (like an anchor, for example). In the absence of additional forces, the boat's motion will be dictated entirely by the speed and direction of the river's current.