1700993363
1700993364
1700993365
7-38
1700993366
1700993367
7-39 ξB＝5cos（4πt－1.71π）cm．
1700993368
1700993369
7-40 略．
1700993370
1700993371
7-41 ν＝3100Hz．
1700993372
1700993373
1700993374
7-42 波形曲线略．
1700993375
1700993376
7-43 ν1＝965Hz，ν2＝1025Hz．
1700993377
1700993378
7-44 ν拍＝15Hz．
1700993379
1700993380
7-45 v＝6.03m/s．
1700993381
1700993382
7-46 m1＝15.3kg，m2＝3.8kg，m3＝1.7kg．
1700993383
1700993384
1700993385
7-47
1700993386
1700993387
7-48 A大＝1.3m，A小＝0.3m，∆t＝150h（小时）．
1700993388
1700993389
1700993390
7-49 t0≥t≥0时段：
1700993391
1700993392
1700993393
t＞t0时段：
1700993394
1700993395
7-50 左侧4μmg/k处．
1700993396
1700993397
7-51 18cm．
1700993398
1700993399
1700993400
7-52
1700993401
1700993402
1700993403
7-53
1700993404
1700993405
1700993406
7-54
1700993407
1700993408
7-55 略．
1700993409
1700993410
7-56 （1）略； （2）T＝2πlsinθ0/vA0．
1700993411
1700993412
