We are given the following parameters:
- The velocity of the conveyor belt: \( v = \sqrt{\frac{gh}{6}} \),
- The coefficient of friction: \( \mu = \frac{5}{3\sqrt{3}} \),
- The person climbs with constant acceleration.
Step 1: Force analysis.
The frictional force is given by:
\[
f = \mu N = \mu mg.
\]
Step 2: Maximum possible acceleration.
The maximum acceleration is found using the equation:
\[
a_{{max}} = \frac{g}{6}.
\]
Step 3: Using the kinematic equation.
Using the kinematic equation \( v^2 = u^2 + 2 a d \), we get:
\[
\left(\sqrt{\frac{gh}{6}}\right)^2 = 0 + 2 \times \frac{g}{6} \times h.
\]
Simplifying, we find:
\[
\frac{gh}{6} = \frac{gh}{3}.
\]
Step 4: Time taken.
Using the equation \( v = u + at \), we solve for time \( t \):
\[
\sqrt{\frac{gh}{6}} = \frac{g}{6} \times t,
\]
which simplifies to:
\[
t = \sqrt{\frac{6h}{g}}.
\]
Final Answer: \( t = \sqrt{\frac{6h}{g}} \) .