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Mechanical Energy Laws

Mass m whirls on a frictionless table, held to circular motion by a string which passes through a hole in the table. The string is slowly pulled through the hole so that the radius of the circle changes from L1 to L2.

Show that the work done in pulling the string equals the increase in kinetic energy of the mass.

Solution Preview

From the conservation of angular momentum, the angular velocity ...

Solution Summary

We use the conservation of angular momentum and v = rw to prove this case.