Energy, work and power — practice question

Points $A$, $B$ and $C$ are on the line of greatest slope of a plane inclined at $30^\circ$ to the horizontal, with $AB = 1\,\text{m}$ and $BC = 1\,\text{m}$, as shown in the diagram. A particle of mass $0.2\,\text{kg}$ is let go from rest at $A$ and slides down the plane. The section from $A$ to $B$ is smooth, while the section from $B$ to $C$ is rough, with coefficient of friction $\mu$ between the plane and the particle.