Dwayne builds a model boat sets it in the water.He points a pocket fan at the sail.Predict what will happen to the boat when Dwayne turns on the pcket fan.Use Newton's tird law to explain your prediction.

The fan and the sail are not in direct contact, so that Newton's third law does NOT strictly say that the forces on the sail and upon the fan are equal and opposite. But that is the answer they probably want you to give.

The force that the fan's air flow exerts on the sail is approximately equal and opposite to the force that the air exerts upon the fan blades. However, there is a slight difference that depends upon the momentum change of the air as it is drawn into the fan and eventually flows past the edges of the sail.