Questions and discussion for this lecture live here. Fire away by hitting Reply below 
In regards to lo does that mean that lo is just the measure of how long a moment is either negative or positive or in other words length for when the moment is either hogging or sagging?
Hey @Chris_Kamau.K - lo is the distance between points of zero moment or points of counter-flexure. The moment between these points may be either sagging or hogging. So, the answer to your question would be yes.
Seán