A.π/2 B.π C.3π/4 D.3π/2
A.20~200Hz B.20~2000Hz C.20~20000Hz D.20~200000Hz
已知平面簡諧波的主程為y=Acos(Bt-Cx),式中A、B、C為正常數(shù),此波的波長和波速為:()
A.A B.B C.C D.D