# Boundary layer thickness - Fluid Mechanics

**Q. Boundary layer thickness is the distance from the boundary to the point where velocity of the fluid is ***- Published on 05 Aug 15***a.** equal to 10% of free stream velocity

**b.** equal to 50% of free stream velocity

**c.** equal to 90% of free stream velocity

**d.** equal to 99% of free stream velocity

**ANSWER: equal to 99% of free stream velocity**