A small block starts slipping down from a point
B on an inclined plane AB, which is making an angle $\theta with the horizontal section BC is
smooth and the remaining section CA is rough
with a coefficient of friction \mu . It is found that
the block comes to rest as it reaches the
bottom (point A) of the inclined plane. If
BC = 2AC, the coefficient of friction is given by
\mu = ktan \theta $ . The value of k is _________.
Choose the correct answer: