[填空题]
An organ pipe is 112 cm a7qd o(+nw: .ctwfv)ye 4 eai:long. What w9lf(7dp( zpfiu/dp ;are the fundamental and first three audible overtones if the plpf pz/i;u ( 7d9fp(dwipe is
(a) closed at one end, $f_{1}$ = Hz $f_{3}$ = Hz $f_{5}$ = Hz $f_{7}$ = Hz
(b) open at both ends?$f_{1}$ = Hz $f_{2}$ = Hz $f_{3}$ = Hz $f_{4}$ = Hz