# Homework Help: Question regarding Elastic Potential Energy

1. Jul 6, 2006

### garyljc

Hey guys ,
I got another question , here goes :

A particle P of mass m is attached to one end of a light elastic string of natural length l whose other end is atached to a point A on a ceiling. When P hangs in equilibrium AP has legth 5/3l. Show that if P is projected vertically downwards from A with speed *squareroot*3gl/2 , P will first come to instantaneous rest after moving a distance of 10l/3 .

What confuses me , is the distance moved . Does it include the natural length or not ? Please show me the proof ... Geeez ... thanks :shy:

2. Jul 6, 2006

### garyljc

hmmm .... no one ? I just need to know does the distance includes the natural length =) Can anyone tell me please ?

3. Jul 6, 2006

### nrqed

The question says that it is projected vertically from A which is the point where the string is attached. So the distance includes the length at rest of the string.

4. Jul 6, 2006

### garyljc

ahhh , got it .... i'm confuse before that lol . thanks = )