3. A coin of mass 5 grams is placed on a vinyl disc rotating on a record player. The distance between the centre of the coin and the centre of the disc is 0.1 m and the coefficient of friction between the coin and the disc is \(\mu\). The disc rotates at 45 revolutions per minute around a vertical axis at its centre and the coin moves with it and does not slide.
By modelling the coin as a particle and giving your answers correct to an appropriate degree of accuracy, find
- the speed of the coin,
- the horizontal and vertical components of the force exerted on the coin by the disc.
Given that the coin is on the point of moving,
- show that, correct to 2 significant figures, \(\mu = 0.23\).