JEE Advance - Physics (2000 - No. 3)
The period of oscillation of a simple pendulum of length $$L$$ suspended from the roof of a vehicle which moves without friction down an inclined plane of inclination $$\alpha$$, is given by
$$2\pi \sqrt {{L \over {g\cos \alpha }}} $$
$$2\pi \sqrt {{L \over {g\sin \alpha }}} $$
$$2\pi \sqrt {{L \over g}} $$
$$2\pi \sqrt {{L \over {g\tan \alpha }}} $$