# A spring is attached to the ceiling by a string with no weights

1. Nov 10, 2013

### vstrimaitis

1. A cylindrical string is made out of thin wire.
• The distance between every loop of an unstretched spring is equal;
• The radius of every loop of the spring is r = 4 cm;
• The length of an unstretched spring is l = 20 cm;
• The mass of the spring is m = 50 g;
The spring is hung on the ceiling by a non-elastic string which has a length of a = 10 cm. When the string is hanging, it has the length of l' = 25 cm.

2.
• What is the constant of the spring (k)?
• What is the period of this system, if the angle, at which it is released, is small?

3. I haven't really solved any problems when the weight is not attached on the end of the spring. Does it work the same way or not? If it does, I'll be able to find k. But I have no idea what to do with the period... Any help at all would be appreciated ^^

2. Nov 10, 2013

### Staff: Mentor

Please add a sketch of the system. It is hard to visualize this based on your post.
If something is connected to a point within the spring, you can split the spring in two pieces and consider them as two springs.

3. Nov 10, 2013

### vstrimaitis

I hope this will clarify the problem at least a little bit.

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4. Nov 10, 2013

### Staff: Mentor

Then you'll have to consider the weight of the spring. For a length x in the unstretched spring (where you need some definition of x), what is the mass below that point? What is the stretching force there? If the total spring has a constant of D, what can you say about each point, and finally the stretching of the whole spring?