The force conversation of angular momentum creates

A body is tied to a wire that go through a hole in a (frictionless) table on which the body is spinning.

The body is spinning while the wire is pulled from beneath the table.
according to conversation of angular momentum the speed of the body should now increase, but in terms of forces... what force is actually increasing the speed? the force of the wire can't do it since it perpendicular to the velocity, (thus not doing any work, and thus the kinetic energy should be the same).

so what force is doing it, and where does it comes from in the atomic level..?

Staff: Mentor

Force and torque are different. The net force is 0, the net torque is not zero.

The torque is the cross product of the weight (down) and the vector from the pivot to the center of gravity. This vector is in the horizontal direction, and therefore the angular momentum changes in that direction which causes the gyroscope to precess.