A gramaphone record is revolving with an angular velocity `omega`. A coin is placed at a distance r from the centre of the record: The static coefficient of friction is `mu`. What will be the value of r for that the coil will revolve with the record?

A body is kept at rest at a distance of 10 cm from the centre of a gramophone disc. If the coefficient of friction between the body and the disc is 0.3, then for what maximum rps of the disc, will the body not be thrown off the disc?

A semicircular wire of radius r is rotating with angular velocity omega in a uniform magnetic field B with its radius as axis. If the resistance of the circuit be R and if the axis of rotation remains perpendicular to B, what will be the average power produced in each period?

If the radius of the earth is R, what will be the distance of a geostationary satellite from the centre of the earth ?

A thin circular ring of mass M and radius R is rotating about its own axis with a constant angular velocity omega . Two object each of mass m are placed gently on the opposite ends of a diameter of the ring. What will be the angular velocity of the ring?

A motorcycle rider, in the 'death-well' show in a circus, is revolving along a circular path of radius r on the wall of the well. If the coefficient of friction between the wall and the tyres of the motorcycle is mu , then what minimum velocity should be maintained by the rider?

A circular coil of radius R carries an electric current i. The magnetic field at a point on the axis at a distance x from the centre of the coil (xgtgtR) varies as