( This ( ( causes ( ( the molecules ) ( to ( ( collide ( with ( the ( container walls ) ) ) ) ( with ( ( ( ( ( greater ( ( force and ) frequency ) ) , ) and ) thus ) ( pressure increases ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ causes) (S (NP (DT the) (NNS molecules)) (VP (TO to) (VP (VB collide) (PP (IN with) (NP (DT the) (NN container) (NNS walls))) (PP (IN with) (NP (NP (JJR greater) (NN force) (CC and) (NN frequency)) (, ,) (CC and) (RB thus) (NP (NN pressure) (NNS increases)))))))) (. .)))
This causes the molecules to collide with the container walls with greater force and frequency, and thus pressure increases.
(ROOT (S (S (VP (VBG Reducing) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS molecules)) (PP (IN in) (NP (DT a) (JJ rigid) (NN container)))))))) (VP (VBZ causes) (NP (NN pressure)) (S (VP (TO to) (VP (VB decrease))))) (. .)))