A disk rotates freely on a vertical axis with an angular velocity of 50 rpm . An identical disk rotates above it in the same direction about the same axis, but without touching the lower disk, at 20 rpm . The upper disk then drops onto the lower disk. After a short time, because of friction, they rotate together. The final angular velocity of the disks is1. 49 rpm2. 21 rpm3. 77 rpm4. 35 rpm5. 42 rpm

Select the best definition for wavelength. the height of an oscillating electromagnetic wave the rate at which electromagnetic waves oscillate. the distance between two crests of an electromagnetic wave. the oscillations of electric and magnetic fields select the best definition for frequency. the oscillations of electric and magnetic fields. the height of an oscillating electromagnetic wave. the distance between two crests of an electromagnetic wave. the rate at which electromagnetic waves oscillate