What must be the initial angular speed, of the top disk be so that when it is dropped onto the bottom disk the final angular speed of the disks is equal in magnitude to the initial angular speed of the lower disk ω1 but opposite in direction? Note: the moment of inertia of a disk of mass M and radius R about an axis through its center and perpendicular to the disk is = 1 2 R 2

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

Which situation will produce the greatest change of momentum

A1-lb collar is attached to a spring and slides without friction along a circular rod in a vertical plane. the spring has an undeformed length of 5 in. and a constant k =25 lb/ft. knowing that the collar is released from being held at a determine, the speed of the collar and the normal force between the collar and the rod as the collar passes through b.