Exam 9: Rotation

The information on a compact disc is scanned by a laser initially at a radius of 2.4 cm and then out to a maximum of 6.0 cm.Because the dimensions of the pit information remains constant with radius the disk motor adjusts so that the tangential velocity remains a constant.What is the ratio of the inner to outer rotational frequencies?

The London Eye,which is a giant Ferris wheel,has a diameter of 135 m.It revolves at a constant rate and takes 30 minutes to complete one revolution.What is the linear velocity of a rider in a capsule that is located at the perimeter of the wheel?

A hoop of mass 50 kg rolls without slipping.If the center-of-mass of the hoop has a translational speed of 4.0 m/s,the total kinetic energy of the hoop is

A record turntable rotates through 5.0 rad in 2.8 s as it is accelerated uniformly from rest.What is the angular velocity at the end of that time?

A body of mass m is whirled at a constant angular velocity on the end of a string of length R.To double the kinetic energy of the body as it whirls while maintaining the angular velocity,the length of the string must be changed to