Question

a coin is kept on a gramophone disc at a distance pi cm, from the centre of the disc. at what minimum frequency it start slipping from that position. ​

Answer 1

Mass of each coin = m Radius of the disc, r = 15 cm = 0.15 m Frequency of revolution, ν = 100 / 3 rev/min = 100 / (3 × 60) = 5 / 9 rev/s Coefficient of friction, μ = 0.15 In the given situation, the coin having a force of friction greater than or equal to the centripetal force provided by the rotation of the disc will revolve with the disc.