A mass m whirls on a frictionless table, held to circular motion by a string which passes though 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.
The Attempt at a Solution
I've already shown that the work done by a central force is path independent. Can I just apply the same manipulations used to get the work energy theorem in cartesian coordinates? I'm really not sure so I could use some guidance here.