The span-wise component of flow over the top surface of the wing flows______

A)
From wing-tip to root
B)
From root to wing-tip
C)
Along the free-stream direction
D)
Perpendicular to the wing upwards

Correct Answer :   From wing-tip to root


Explanation : The pressure imbalance is such that there is a low pressure region on top and high pressure region at the bottom. This creates a flow from the bottom surface towards the top surface of the wing. Naturally, the flow moves from the wing-tips towards the wing root.