Discuss the meaning of the result for total energy in a whole mass spring system

[hsut]

Homework Statement

Had to work out the total energy in a mass spring system (Part d of question), which has been found to be:

(v^2*m/4)[sin^2(nt) + sin^2(3nt)]


The next part of the question (e) says to 'Discuss the meaning of your result to part (d) above'

And I have no idea what to write! It is worth nearly 10% of the whole assignment! Any help would be much appreciated.

Thanks

 

[voko]

Your expression for total energy depends on time periodically. This cannot be true. It must either monotonically decay with time (if friction/resistance is present), or be constant.