Question

the span of broad jump depands upon

Answer 1

move your centre of mass as less as possible.. lean a bit foreward before taking off your centre of mass will shift a bit foreward..
and while landing put legs foreward keeping centre of mass behind..
and bend knees as you land to get a bit balance
..... dont lean too much or you might slip... good shoes with good friction/ grip helps here....
use your thigh muslces and NOT the calf muscles... your knee joint should be the one moving more... not only ankle...
try to pop yourself up at 45º
try to pop up at maximum speed.. swoop down before jumping to get maximum speed...
dont go as "lets see how much can i jump ..." instead think.. hmm.. thats the line i have to cross.." while practicing during real time .. aim for the farthest one!
and practise