- #1

skrat

- 748

- 8

## Homework Statement

A polymer consits of ##10^{20}## monomers, each 2 nm long. One end of the polymer is hanged at the ceiling on the other end, we have a load of ##4\cdot 10^{-10}g##.

Calculate the average potential energy!

## Homework Equations

## The Attempt at a Solution

Well... I don't know...

Each monomer adds ##acos\vartheta ## to the total length. So... all monomers together ##\sum_{i=0}^{N}acos\vartheta _i ## Now how do i get the average value from that? That i don't know...

I also tried using phase integral ##e^{-\beta F}=\int_{0}^{2\pi }exp(\beta mg\sum_{i=0}^{N}acos\vartheta _i )d\varphi ## from where the potential energy would be equal to ##\frac{\mathrm{d} \beta F}{\mathrm{d} \beta }## ...

Can anybody please help me here? Thanks!

So the key here is to somehow calculate the average ##cos\vartheta ## where ##\vartheta ## can be anything between 0 and ##\pi##

Last edited: