tarzan, who weighs 688 n, swings from a cliff at the end of a vine 18 m long (fig. 8-40). from the top of the cliff to the bottom of the swing, he descends by 3.2 m. the vine will break if the force on it exceeds 950 n. (a) does the vine break? (b) if no, what is the greatest force on it during the swing? if yes, at what angle with the vertical does it break?