Question 851074
The posterior of the train moves the train-length in that 5 seconds.  That is what to find.


{{{(30*km/hour)*5*seconds*(1*hour/(60*minutes))(1*minute/(60*seconds))=d}}}
{{{(30*5)/(60*60)}}}
{{{(1/2)(1/12)}}}
{{{highlight(1/24)}}} kilometers