A sliding puck analyzed from an inertial reference frame

[Raziel2701]

Homework Statement

Located here:http://imgur.com/qP9fd.png"

The Attempt at a Solution

I don't know how to do this problem.

First of all how do I approach it? Should I do a free-body diagram? Should it be done at position 1? How do I account for the different frame of reference? How is this going to affect the equations for kinetic energy?

I would like to know if I'm thinking of this right:

I should find the tension, somehow, so that I may find the work done by this force. Knowing the work, I can use the work-kinetic energy theorem to find velocity and if this plan is right, then I'll probably take it from there and come back if I get stuck again. However, this business with a different reference frame is, unknown to me, I don't know how it affects things. I was ready to say that the velocity is zero at position 1, since to me it seems like it would be zero relevant to an object moving at a constant velocity, but now I need to work something out to show that it's not.

So I guess I need help with part a first.

 

[tiny-tim]

Hi Raziel2701!

(This is on horizontal ice, isn't it … so that we can ignore friction and gravity?)

Should I do a free-body diagram? Should it be done at position 1?

Well, there's only one force on the puck, so it won't be much of a diagram, but yes you can draw it if you like.

If you do, you should draw it at a general position θ.

How do I account for the different frame of reference?

You don't do anything special.

You just pretend that the moving frame of reference is actually stationary …

in other words: you pretend that the bead is fixed, and the puck is moving in a (horizontal) circle round the bead …

so how will the speed V of the puck (you can't use "v", that's already in use for the bead ) depend on θ?

Once you've found V, find T, and rest should be easy. ​