Q.
Calculate the time period of a simple pendulum of length L suspended from the roof of a vehicle which moves without friction down an inclined plane of inclination angle α .
Vehicle is moving down the frictionless inclined surface so, its acceleration is gsinα . Since vehicle is accelerating, a pseudo force m(gsinα) will act on bob of pendulum which cancel the sinα component of weight of the bob.
Hence net force on the bob is Fnet=mgcosα or net acceleration of the bob is geff=gcosα ∴ Time period T=2πgeffl=2πgcosα1