Engineering Dynamics Question - SHM

[danza]

I'm stuck. I have a question on simple harmonic motion and a solution to it, and I'm still stuck.

Basically, I can't get my head around how the solution is arrived at. It's just not going in/making sense.

Some fun pictures:

Relevant tutorial section (even with this I can't get my head around things)

Question

Solution

Can anyone explain/help me remember how this is done in steps? It seems like some of the working is missing from the solution, or that there is a gap in my knowledge that's not letting me fill in the blanks.

I knew I shouldn't have waited 2 years before topping-up to a degree. :/

Any assistance would be spiffing.

 

[danza]

Thanks guys, I will have a look at the links you've provided.

Hopefully I'll be able to get back on track and it'll begin to make a bit more sense now!