A horizontal disc rotating about a vertical axis makes 100 revolutions per minute. A small piece of wax of mass 10 g falls vertically on the disc and adheres to it at a distance of 9 cm from the axis. If the number of revolutions per minute is there by reduced to 90, calculate the moment of inertia of the disc.

A gramophone disc rotates at 60 revolutions per minute. A coin of mass 13 g is placed at the disc at a distance of 8.0 cm from the centre. Calculate centrifugal force on the coin.

A man stands on a rotating platform, with his arms stretched horizontally holding a 5 kg weight in each hand. The angular speed of the platform is 30 revolutions per minute. The man then brings his arms close to his body with the distance of each weight from the axis changing from 90cm to 20cm. The moment of inertia of the man together with the platform may be taken to be constant and equal to 7.6 kg m^2 :- Is kinetic energy conserved in the process? If not, from where does the change come about?

A man stands on a rotating platform, with his arms stretched horizontally holding a 5 kg weight in each hand. The angular speed of the platform is 30 revolutions per minute. The man then brings his arms close to his body with the distance of each weight from the axis changing from 90cm to 20cm. The moment of inertia of the man together with the platform may be taken to be constant and equal to 7.6 kg m^2 :- What is his new angular speed? (Neglect friction.)

Four sphere each of mass 10 kg and of radius 20 cm are placed at the four cornes of a square of side 100 cm. Calculate the moment of inertia of the system about an axis coinciding with side of the square (given moment of inertia of sphere = 2/5 MR^2 )

A rectangular coil 25 cm xx 10 cm and having 700 turns rotates about an axis at right angles to a magnetic field of 20 gauss at 1,500revolutions per minute. Calculate the maximum vlaue of the e.m.f. generated in the coil.

A wheel rotates making 20 revolutions per second. If the radius of the wheel is 35 cm., what linear distance does a point of its rim traverse in three minutes ?

Four sphere each of mass 10 kg and of radius 20 cm are placed at the four cornes of a square of side 100 cm. Calculate the moment of inertia of the system about an axis coinciding with diagonal of the square. (given moment of inertia of sphere = 2/5 MR^2 )

A rectangular coil of dimensions 40 cm xx25 cm having 1000 turns rotates in a uniform magnetic field of strength 0.08 Wbm^(-2) about an axis perpendicular to the field. If the coil makes 300 revolution per minute, find the instantaneous emf when the plane of the coil make and angle of 0^(@)

A rectangular coil of dimensions 40 cm xx25 cm having 1000 turns rotates in a uniform magnetic field of strength 0.08 Wbm^(-2) about an axis perpendicular to the field. If the coil makes 300 revolution per minute, find the instantaneous emf when the plane of the coil make and angle of 45^(@)