# A train is moving up an incline of inclination $\pi/6$ with constant velocity. A bob is hung on the ceiling. The angle made by the bob with normal?

Mass of bob is 1 kilogram. Let the angle of Bob with the normal be $\phi$ the force acting on bob along the axis of motion is $$mg\cos(\phi)$$ Now as this train is having zero acceleration, bob must move with zero acceleration so the force acting on bob due to gravity ie $$mg\sin(\pi/6)$$ Therefore $mg\sin(\pi/6) = mg\cos(\phi)$ Then phi must be $\pi/3$ but the answer my book has is different. What's the mistake I'm making?