Question

Water is placed between two parallel plates. The bottom plate moves to the right at constant velocity V and the top plate is stationary. The water velocity profile shown below is observed at steady-state conditions (you are looking at a side view of the plates and the water between the plates). Ignoring edge effects in this flow system, water moves in the x-direction only and therefore has only x-momentum. In which direction is the x-momentum being transferred? (The graph looks like a triangle with longest arrow at bottom)

A. Transfer is in the -y direction (downward in the figure) because the velocity arrow bet bigger as you move towards the bottom plate
B. Transfer is in the +x direction (to the right in the figure) because that's the same direction as the velocity
C. Transfer is in the +y direction (upward in the figure) because momentum is transported from a region of high momentum (near bottom of plate) to low momentum (near top of plate)
D. Transfer is in the +x direction (to the right in the figure) because the drag force on the plates caused by friction is in the direction of the flow
E. Transfer is in the -x direction (to the left in the figure) because momentum transfer and velocity act in opposite directions to each other.

Answer 1

The x-momentum in this flow system is being transferred in the upward direction because momentum is transported from a region of high momentum to low momentum.

Step-by-step explanation:

The x-momentum in this flow system is being transferred in the +y direction (upward in the figure).

This is because momentum is transported from a region of high momentum (near the bottom plate) to low momentum (near the top plate).

As the velocity arrow gets bigger as you move towards the bottom plate, the x-momentum is transferred upwards.