The tank containing gasoline has a long crack on its side that has an average opening of 10 μm. The velocity through the crack is approximated by the equation , where y is in meters, measured upward...

The tank containing gasoline has a long crack on its side that has an average opening of 10 μm. The velocity through the crack is approximated by the equation
, where y is in meters, measured upward from the bottom of the crack. Find the shear stress at the bottom, y = 0, and the location y within the crack where the shear stress in the gasoline is zero. Take
 .