When the engine of the plane is running, the vertical reaction that the ground exerts on the wheel at A is measured as 616lb . When the engine is turned off, however, the vertical reactions at A and B are 520lb each. The difference in readings at A is caused by a couple acting on the propeller when the engine is running. This couple tends to overturn the plane counterclockwise, which is opposite to the propeller's clockwise rotation.
The image is of a plane who's wheels are spread apart by 12 ft and on the ground. The left wheel being point A and the right wheel being point B. It also has an arrow around the front propeller in the clockwise direction.
A) When the engine of the plane is turned on, determine the magnitude of this couple.
B) Determine the magnitude of the reaction force exerted at B when the engine is running.
Express your answer to three significant figures and include the appropriate units.