Work-Energy Theorem: Homework Statement & Solution

AI Thread Summary
The discussion focuses on a homework problem involving a mass in circular motion on a frictionless table, where the radius changes as the string is pulled. The key task is to demonstrate that the work done in pulling the string corresponds to the increase in the mass's kinetic energy. Participants suggest using conservation of angular momentum and the definition of work done by the tension in the string, along with integration techniques, to solve the problem. There is a mention of path independence of work done by a central force, indicating a potential approach to the solution. Overall, the conversation emphasizes applying fundamental physics principles to derive the relationship between work and kinetic energy in this scenario.
jgens
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Homework Statement



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.

Homework Equations



N/A

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.
 
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hi jgens! :wink:

i'll guess that they want you to use conservation of angular momentum , the definition of the work done (by the tension in the string), and a bit of integration :smile:
 
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