【多选题】频率相近的两个同方向的简谐振动合成后,会产生拍现象,拍现象的特征为( )
【单选题】The author seems to be especially impressed by the fact that ______.
A.
Mason, a responsible citizen, resisted for so long the obligation to represent his state in politics
B.
Mason, having so little political inclination, turned out to be such an influential statesman
C.
Mason was willing to leave home and family for public service
D.
Mason could be a devoted family man and a statesman at the same time
【单选题】与金铸币本位制相比,金块本位制和金汇兑本位制对汇率的稳定程度
【单选题】设两个同方向简谐振动,二者振幅相同,初相也相同,周期分别为T1、T2,频率分别为ν1、ν2,【图片】,则这两个振动的合振动:
【单选题】两个同频率同方向的简谐振动,周期为20ms,振幅分别为1cm和3cm,当两者相位差为0时,合振动的振幅是:
【单选题】图中(1)和(2)表示两个同方向,同频率的简谐振动的振动曲线。则(1)和(2)合成振动的振幅为 ,初位相为 ,周期为 .
【简答题】当两个同方向的简谐振动合成为一个振动时,其振动表式为x=Acos2.1tcos50.0t,式中t以s为单位,求各分振动的角频率和合振动的拍的周期.
【单选题】两个同频率同方向的简谐振动,周期为20ms,振幅分别为1cm和3cm,当两者相位差为 时,合振动的振幅是:
【单选题】The whole room fell into an ________ silence and we knew that he would soon explode with anger.