For a plane to be able to fly clockwise in a horizontal circle as seen from above, in addition to exerting a force downwards on the air
A) it must be increasing its speed.
B) it must exert a force on the air that is directed to the plane's left side.
C) it must exert a force on the air that is directed to the plane's right side.
D) it does not need to exert a force: it must only move the wing flaps out.
E) it only needs to deflect the air without exerting any additional force on the air.

Question

Quizplus · Accepted Answer

In order to fly in a horizontal circle, the plane needs to turn towards its left side. This requires the plane to create a centripetal force towards the center of the circle. Since the plane is already exerting a force downwards on the air, it needs to exert an additional force towards its left side which will create the necessary centripetal force. This can be achieved by deflecting the air using the ailerons on the wings to create a lift force on the left wing and a corresponding drag force on the right wing, which will turn the plane towards the left. Therefore, option B is the best choice.

For a Plane to Be Able to Fly Clockwise in a Horizontal