Rotation And Revolution

A fly wheel of moment of inertia I is rotating at n revolutions per sec. The work needed to double the frequency would be -

A rod of mass 1kg and length 6.25 m is hinged at one end of a smooth horizontal surface. A force of magnitude (pi)/(3)N acts it such that it is always perpendicular to the rod. Find the time (in sec.) when the rod has rotated one revolution?

A chain of 125 links is 1.25 m long and has mass of 2 kg with the ends fastened together. It is set for rotating at 50 revolutions per second. The centripetal force on each link is

A table fan rotating at a speed of 2400 rpm is switched off and the resulating variation of the revolution/minute time is shown in Fig. The total number of revolutions of the fan before it comes to rest is

A closed coil having 100 turns is rotated in a uniform magnetic field B = 4.0 X 10^(-4) T about a diameter which is perpendicular to the field. The angular velocity of rotation is 300 revolutions per minute. The area of the coil is 25 cm^2 and its resistance is 4.0 Omega. Find (a) the average emf developed in the half a turn form a position where the coil is perpendicular to the magnetic field, (b) the average emf in a full turn and (c) the net charge displaced in part (a).

Find torque required so that a coin of mass 1kg rotates 25 revolution in 5 sec starting from rest.

The kinetic energy of a body rotating at 300 revolutions per minute is 62.8 J. Its angular momentum (in kg m^(2)s^(-2) ) is approximately