8. A 15-kg box slides down a smooth inclined surface as shown in the figure below.Determine the terminal velocity of the box if the 0.1 mm gap between the box and the surface contains gasoline at 60 °F. Assume the velocity distribution in the gap is linear, and the area of the block in contact with the gasoline is 0.1 m². [11 points]

Fig: 1

Fig: 2