P18_091.PDF

91. Since they oscillate out of phase, then their waves will cancel (producing a node) at a point exactly

midwaybetweenthem(themidpointofthesystem,wherewechoose x =0). WenotethatFigure18-14,

andthe n =3caseofFigure18-15(a)havethisproperty(ofanodeatthemidpoint). Thedistance∆ x

betweennodesis λ/ 2,where λ = v/f and f =300Hzand v =343m/s. Thus,∆ x == v/ 2 f =0 . 572m.

Therefore,nodesarefoundatthefollowingpositions:

x =

∆ x =

0 . 57m

1 . 14m

x = ± 3∆ x = ± 1 . 72m

2∆ x =

x =