( ( The ( support force ) ) ( ( is ( ( tilted forward ) ( because ( it ( ( 's ( at ( right angles ) ) ) ( to ( the slope ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN support) (NN force)) (VP (VBZ is) (VP (VBN tilted) (ADVP (RB forward)) (SBAR (IN because) (S (NP (PRP it)) (VP (VBZ 's) (PP (IN at) (NP (JJ right) (NNS angles))) (PP (TO to) (NP (DT the) (NN slope)))))))) (. .)))
The support force is tilted forward because it's at right angles to the slope.
(ROOT (S (NP (NP (NNP Instruments)) (SBAR (WHNP (WDT that)) (S (VP (VB measure) (NP (NP (DT the) (NN angle)) (PP (IN of) (NP (NP (DT the) (NN slope)) (PP (IN of) (NP (DT a) (NN volcano)))))))))) (VP (VBP are) (VP (VBN called) (NP (NN tilt) (NNS meters)))) (. .)))