( ( With ( less gas ) ) ( , ( ( the balloon ) ( ( begins ( to ( drop ( with ( increasing velocity ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN With) (NP (JJR less) (NN gas))) (, ,) (NP (DT the) (NN balloon)) (VP (VBZ begins) (S (VP (TO to) (VP (VB drop) (PP (IN with) (NP (VBG increasing) (NN velocity))))))) (. .)))
With less gas, the balloon begins to drop with increasing velocity.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (PRP you)) (VP (VBP add) (NP (NP (NNS moles)) (PP (IN of) (NP (NP (NN gas)) (PP (TO to) (NP (DT a) (NN baloon)))))) (PP (IN by) (S (VP (VBG blowing) (NP (PRP it)) (PRT (RP up)))))))) (, ,) (NP (DT the) (NN volume)) (VP (VBZ increases)) (. .)))