( ( Uphill/downhill ( in ( ( uniform gravity ) ( in ( a vacuum ) ) ) ) ) . )
(ROOT (S (VP (VB Uphill/downhill) (PP (IN in) (NP (NP (JJ uniform) (NN gravity)) (PP (IN in) (NP (DT a) (NN vacuum)))))) (. .)))
Uphill/downhill in uniform gravity in a vacuum.
(ROOT (S (NP (NNP Gravity)) (VP (VBZ causes) (S (NP (NNS rocks)) (VP (TO to) (VP (VB roll) (ADVP (RB downhill)))))) (. .)))